A mouse squeaks, a pig squeals.

Squealing is more of an action. Like a little girl might squeal in excitement. Or a little mouse or animal might squeal when being hurt. You wouldn't use squeak in those examples. Squeaky is more descriptive. Like someone can have an annoying squeaky voice. A door might squeak when you open it. When something like a floor or table is really clean someone might call it "squeaky clean" because it would squeak if you ran your finger over it. When you slide against a leather couch it might squeak or make a squeaky sound etc

Squeaky is usually used to describe the sound of new shoes or the sound made by furniture, for example. Squealing describes the terrified sound of animals when in fear of their lives very often.

Both words can be used for similar things, but there might be a slight difference with the emotion attached to the words. Squeaked = sometimes a shorter, high-pitched noise, can be used for somebody who is frightened (She let out a squeak when she saw the spider.) Squealed = sometimes a longer, high-pitched noise, can be used for somebody who is experiencing distress (The pig squealed as it ran away from the fox.) It's a little tricky...they are similar enough that it can be used to describe a lot of high-pitched noises but certain phrases use each word more often. e.g. a mouse squeaks, a door or floorboard squeaks a pig squeals, a car tire can squeal Sorry, I hope that helps a bit.