What are the differences between Vinci and Small World?
There is an excellent comparison of the two here.  Some highlights:


Vinci has one big set of powers and you draw two for each race.  Small World splits them into Race Powers and Abilities, preventing some combinations from occurring.
Vinci charges you two points for each race you skip over, Small World only 1.  This modifies the dynamics of which races you might choose.
The end game conditions in Vinci are reaching a certain number of points, making the length variable.  Small World has a fixed number of turns based on number of players.
Small World has different maps for different numbers of players, and you always get the same number of tokens for a race/power combo.  Vinci only had one map, but varied the number of tokens a power combo started with based on the number of players.
Small World adds a reinforcement dice which gives you a random chance to take over a single province that you wouldn't be able to conquer normally at the end of your turn.