All ready and all right (two words) mean that everything is ready or everything is correct / OK:
– The students are all ready for the test.
– Your answers are all right. or All your answers are right.
Already means that something happened earlier than expected:
– He’s only 14 and he’s already graduated from high school – he’s a genius!
– The repairs on my car are finished already? Wow, that was fast.
– You don’t have to wash the dishes – I’ve already done it.
All right can also mean OK/uninjured, acceptable, or average.
– Are you all right?
– If it’s all right with you, we’ll reschedule the meeting. or If it’s acceptable to you
– The food at that restaurant is all right. or Average; not especially great, but not bad either
Alright is a variant of “all right” that is not considered correct, even though many people use it informally.