Is there's difference between "i love you" and "ily"?

He has said both things to me. I love you and ily. recently he's been saying ily, mainly because i said ily instead of spelling it out because i was annoyed at him at the time. when i said "i love you, goodnight" he said "ily too" is it a big deal since we've both said both?
Is there's difference between "i love you" and "ily"?
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