Travel Carcassonne is, as the name says, a Travel Edition of Carcassonne.
The rules of the game are (mostly) the same, but there are some changes between the two editions:
No Expansions: The tiles size of the Travel Edition is smaller than the regular game, so it is not possible to add any expansion for the regular game. EXCEPT The Phantom expansion.
Le Sac as counting table: The game includes a bag for the tiles that is printed with a counting table. (Le Sac is missing from the 2012 reprint edition, which instead comes with a counting table printed on the back of the box.)
Third Edition farm scoring: The Rio Grande edition features, for the first time, the current, Third Edition Hans im Glück farm scoring.