Super 8 was awesome. I huge throwback to their younger days of filming. I've never thought about it being a sort of prequel. Looking at pictures online they certainly do seem very similar. The creature from Super 8 escaped off Earth at the end. Also it is said the creature from Cloverfield was "immature and suffering from separation anxiety." "It is not out there just killing. It is confused, lost, scared. It's a newborn". This creature seemed much larger than the one in Super 8 which seemed rather intelligent. Also, "Reeves said the creature had "been down there in the water for thousands and thousands of years".[12]"
Would be interesting if he ties them together. Hopefully there is a Cloverfield 2 to done soon.
Lots of really interesting information of Cloverfield here,
http://cloverfield.wikia.com/wiki/Cloverfield_Monster On further reading I really don't think it is the same creature, possible, but I HIGHLY doubt it. Plus I believe before the movie was released J.J. Abrams said it wasn't a prequel.