Radiant

The Radiant team is located on the bottom-left side of the map, which has a brighter, happier theme. The Radiant side of the map contains fully grown trees, green grass, and bright blue light glowing near the Radiant ancient. While the lighter theme may carry good connotations, the Radiant is not purely good.

From a gameplay perspective, there are many key differences between the Radiant side of the map and the Dire side. The layout of both sides are very different, and can be viewed here. Here are a few key differences.
 * Roshan is located on the Dire side, near the bottom rune spawn location.
 * Unlike the Dire side, Radiant's top lane has a convenient way to pull using the nearby Hard Camp.
 * Before 6.86c version, it is possible to block 2 jungle camps with 1 ward on in the Radiant jungle.

Trivia
Earlier in the development of Dota 2, some heroes were affiliated with the Radiant.

In DotA when playing the Normal game mode (also called "Pick Mode"), players could only pick Sentinel heroes while on the Sentinel team, and vice versa. To be able to pick heroes from both sides, an -ap (all pick) gamemode modifier was needed. This game mode is not present in Dota 2.

The heroes affiliated with the Sentinel side in DotA (counterpart of the Radiant side in Dota 2) are:

There is a HUD skin related to Radiant aesthetics, Radiant Ore