I'm 20+5 and have only just distinguished the difference between a kick/punch and a wriggle. Kicking/punching feels like I'm being prodded from the inside where as wriggling feels different, it actually feels like wriggling to me. I wouldn't describe what I feel as fluttering or butterflies, and it no longer feels like bubbles popping either! You will know when your baby is moving for sure :)
Depends on how many weeks you have. Im 21 weeks and 3 days expecting my second baby and her first movements used to be like butterflies inside flying around my lower abdomen, but now that im 21 weeks feels like a snake moving in my belly hahaha, but it feels amazing.