Garage

This is where all your stolen cars are stored. You have a dropdown list in case you wanna choose/see only cars in one particular city. You can select all cars, unselect all cars, ship or sell, safehouse or unsafehouse, repair cars and crush them (more on crushing on 'nick a car')

Safehouse
There's one good for the safehouse, virtually three.
Virtual- one: Some people believe safehoused cars bring better heists, OC's and races and what not. I personally don't. If you wanna believe it go ahead, safehousing a car costs $10,000
Real- two: When you select all cars, safehoused ones will not be selected. Good when you're crushing using the select all cars key. You'll crush all the ones you haven't safehoused (which means you gotta safehouse all the good ones).
Kinda virtual- three: Sometimes, feds will come and confiscate one of your cars, randomly. Safehoused cars can't be confiscated. I've been playing since 2.2 and this happened to me twice in my whole Omerta life... Not something you should worry about.