Simple Adhesive Guide:

Use the ready mixed tub adhesive for fixing wall tiles up to around 300mm in the bathrooms and kitchens.

Use the yellow powder bags for any installation on the wall or if you're not a confident tiler on the floor.

A professional tiler may want to use the red bags for floors because it dries quicker.

There are very few scenarios when you need to use the green bag because its best practice not to tile on wood but use this if you do and also for screeds that are not fully dry.

Powder bags available in grey or white. Use white if you're using a light coloured grout and grey for dark. The only time it is important to get the correct colour is when  you must use a rapid setting white adhesive for all light coloured natural stones so that they are not stained by the dark colour.