The Nagara style has its origin in the structural temples of the Gupta period, especially the Dashavtara temple of Deogarh and the brick temple of Bhitargaon.
Two distinct features of the Nagara style are - planning and other elevation.• The plan is square with a number of gradual projections in the middle of each side which Imparts it a cruciform shape. When there is one projection on each side, it is called ‘triratha’, two projections – ‘Pancharatha’, three projections – ‘Saptharatha’ and four projections –‘Navaratha’. These projections can occur throughout the height of the structure.• In elevation it exhibits a tower (shikhara) gradually inclining towards in a convex curve.• The projections in the plan are also carried upwards to the top of the shikhara.
It is also called the rekha shikhara.
In Nagara style temples, the structure consists of two buildings, the main shrine taller and an adjoining shorter mandapa. The main difference between these two is the shape of the shikhara. In the main shrine, abell shaped structure further adds to the height. In this style, the temples mainly are formed of four chambers, first the ‘Garbhagriha’, then second Jagmohan’, third ‘Natyamandir’ and fourth chamber the ‘Bhogamandir’.
Originally in nagara style there were no pillars.
By the eighth century the Nagara style emerges in its characteristic form. The Nagara style exhibits distinct varieties in elaboration. The temple belonging to the Nagara style of architecture may be seen from the Himalaya to the north of Bijapur district in the south, from the Punjab in the west to Bengal to the east. As a result, there are local variations and ramifications in the formal development of the style in the different regions. Such variations are cause by local conditions, by different directions in development as well as assimilation of unrelated trends. However, the cruciform plan and the curvilinear tower are common to every Nagara temple.
The Lingaraja temple, dating from the 11th century, is one of the grandest and is regarded as a gem of Nagara architectural style. This temple consists of the sanctum, a closed hall, a dancing hall and a hall of offerings. The sanctum is Pancharatha on plan. The lower register of the wall is decorated with Khakhara-Mundis and the upper with Pidhamundis. The Khakhara Mundis contains on the corner Rathas figures of eight Regents and on the flanking Rathas miscellaneous friezes. The Pidhamundis are inset with images of various Brahmanical gods and goddesses. The famous temple of Jagannatha at Puri is roughlycontemporaneous with the Lingaraja. It shows the same mature plan as the latter, but is even loftier and isnearly 56.70 m high.
Source : http://en.wikipedia.org/wiki/Hindu_temple_architecture
The Dravida Architectural style is associated with the temples of southern India or Deccan. The earliest traces of Dravida architectural features go back to Gupta period and are not restricted to the far south i.e. in Gupta period these traces occur in northern and central India along with Deccan, like in the Parvati temple at Lad Khan, Kont Gudi and Meguti temples at Aihole.
The outstanding and the common characteristics of the Dravida style is the pyramidal elevation of the tower (vimari), which consists of a multiplication of storey after storey slightly reduced than the one below, ending in a domical member, technically known as the stupi or stupica.
The storey in the later period became more and more compressed so much so that they are almost hidden under a profusion of details which became characteristic of the subsequent evolution of the style. In plan the Dravida temple presents a square chamber as the sanctum cell within the square enclosure serving as the pradakshina (circumambulatory passage).
The pillared halls and corridors, and the immense gopurams (gateways) are the additions of the later date to the Dravida temples.
The two most important characteristics of Dravida temple architecture is :• Temples of this style has more than 4 sides in the sanctum and• Tower or Vimana of these temples are pyramidal.
Pillars and pilasters are vastly used in this architectural style.
In different temples ‘dedicated pavilions’ can be seen like Shiva templeshave dedicated mandapa of ‘nandi’ the bull or Vishnu temples have ‘garuda mandapa’.
Boundary walls in south Indian temples were built in early medieval period where north Indian temples were not walled.
In temples built in the Dravida style, the square inner sanctum is set within a large covered enclosure. The external walls are divided into niches by pilasters.
The Kailasanatha temple is a major example of the Dravida Architecture. The Kailasanatha temple complex is situated at Kanchi as a joint venture of Rajasimha or Narasimhavarman II and his son Mahendra III. The main Vimana facing east is four storeyed, and is essentially a square structure up to the giva. This is placedabove the sikhara and is usually octagonal. The main sanctum has a large fluted, sixteen-faced, polished,basalt linga with an immense circular linga-pitha occupying almost the entire floor of the sanctum. There is a detached multi pillared oblong mandapa in front. This is longer on its north-south axis and with its containing pilasters Vyala based while in the west these are of the plainer type. The whole is surrounded by a prakara with a gap in the middle of its east side and enclosing an open court all rounds.
It emerged during early medieval period.
It is a hybrid style that borrowed from the northern and southern styles. So, it is a mixture of both Nagara and Dravida styles of temple architecture.
Temples built in the Deccan under the later Chalukyas of Kalyani and Hoysalas are considered examples of this style.
Vesara style reduces the height of the temple towers even though the numbers of tiers are retained. This is accomplished by reducing the height of individual tiers.
The semi circular structures of the Buddhist chaityas are also borrowed in this style, as in the Durga temple of Aihole.
Many temples in Central India and Deccan have used the Vesara style with regional modifications. The Papanatha temple (680 AD) in particular and someo ther temples to a lesser extent located at Pattadakal demonstrate panache for this stylistic overlap‛.
The trend of merging two styles was started by the Chalukyas of Badami (500-735 AD) who built temples in a style that was essentially a mixture of the Nagara and Dravida styles, further refined by the Rashtrakutas of Manyakheta (750-983 AD) in Ellora, Chalukyas of Kalyani (983-1195 AD) in Lakkundi, Dambal, Gadag etc. and epitomized by the Hoysalas (1000-1330 AD).
Most of the temples built in Halebid, Belur andSomanathapura are classified under this style.