word usage - "Would" & " Used to"

"Would " & " Used to ".
They both are used for repeated action in the past tense. Then what is the difference between them?

Answer

'Used to'and'would' are modals; though both apply to habitual action of the past,'would' carries with it a sense•• had it been so it might have been such••examples of which are there in UNCLE PODGER's absurdities. As regards use of the two,you're your best judge. Ask yourself--does it sound fine?