Indian sweets are so rich, that they are more like a dessert, and in the sweet shop there is no distinction between the two.

TYPES OF SWEETS
Sweets generally fit into categories based on their main ingredient, their shape, or the method of production.
BARFI
Are types of fudge. Their name comes from the Persian word for snow and in their original form they were probably all white. Barfi are based on Khoya, a milk product, and are very sweet. Those with ground nuts or flour in them have a grainier texture than the plain milk (dhoodh) versions.
SANDESH
Based on Chenna mixed with sugar, are one of the finest Indian sweets. The name means 'news' and the sweets were originally sent to friends by messenger as a means of enquiring after them. Sandesh can be made in a variety of textures and flavours and are often pressed into decorative moulds.
HALVA
These have a thick, pudding like texture and are based on ingredients such as semolina, grated carrot, besan flour and pulses. Sweet-makers in the East are called 'Halvais'.
LADDU
These sweets are named for their ball shape rather than their ingredients. They are made with a Besan (gram) flour or coarse flour dough which is pressed in patties, deep-fried, then crumbled and shaped into balls with sugar, ghee, spices and nuts. Laddus can found in many variations.
DEEP-FRIED
These sweets are fried in oil / butters and then soaked in sugar syrup such as Jalebi.

MILK-BASED
These sweets and desserts range from Bengali specialities such as Rassogulas and Gulaab Jamons to Kheer (Rice pudding) and Sevian (milky vermicelli dessert)

MILK-BASED SWEETS
Milk is often used in sweet-making. It is either boiled for prolonged periods until it thickens, or is converted to a type of fresh cheese (Paneer) by coagulating it with lemon juice.
RABRI or RABADI is milk at a quarter of its original volume, eaten as a thick, creamy pudding, or as a sauce for sweets such as Ras Malai.
KHOYA, a fudgy solid mass, is milk at an eighth of its original volume. It is the main ingredient in many milk-based sweets.
CHENNA is paneer sweetened with sugar and is the ingredient on which Rassogula and Sandesh are based.
MALAI is the Hindi word for cream. Malai varies in thickness.

DECORATIONS
Indian sweets are required not only to taste good, but also to look fabulous. They are often coloured pink, yellow or green, studded with nuts or sultanans, or covered with a gossamer-fine layer of gold or silver leaf (Varak). Though everyday sweets are not as fancy, those sold around festival times are made more elaborate with extra decorations.

FLAVOURINGS
Saffron, cardamom, rose essence, kewra, khus, coconut, pistachio and almond are the most common flavours. Unrefined sugars such as gur or jaggery also add flavour and are often preferred to refined sugar.

Source: http://www.mukhtars.co.uk/what_is_mithai.html