The word Squeal and laugh describes variety of emotional reactions.
Human emotions have external expressions which may take variety of forms. Unpleasant emotions may be expressed in the form of tears, frown, etc. whereas positive emotions may be expressed in the form laughter, smile, chuckling, etc.
Squeal and laugh are the sounds that are created while expressing a particular emotion. Laugh generally indicate joy, delight, pleasure, happiness, joviality, etc. whereas Squeal is shrill noise or cry which may be created by the objects or by animals like pig or by human while expressing unpleasant emotions.