Green card is the card you first start off with to get all the way to the top you can use green card on a monument called harbor.

Blue card can be found in a monument called harbor. Blue cards can be used on many monuments such as water treatment, train yard Oil rig and more.

Red card is the highest tier card you can get. This card is very important if you want to run high tier monuments such as launch sites,oil rigs, large oil rigs and more. (All cards have a durability if you keep using them they will eventually break you only have 4 swipes.