They are different. Bloodworms are the larvae of a non-biting midge (Chironomidae). They are red and live on the bottom of stagnant water among decaying plant material. When disturbed they swim with a 'figure of 8' looping motion. The eggs of bloodworm midges look like a red coiled spring in a tube of jelly a few mm long.

Mosquito larvae are the larvae of biting mosquitoes (Culicidae). They are brown and hang upside down from the surface of stagnant water. When disturbed they swim downwards with a looping motion. The eggs of mosquitoes are arranged in a black boat-shaped raft a few mm long.

Both are available frozen from specialist suppliers.