OK Im bored so Ill do some hunting here and help you out
micro worms are....
A tiny earthworm, so small you can barely see them, and then only if you strain your eyes. The perfect food for tiny fish.
pic from
www.lfscultures.com
vinegar eels are...
An extremely tiny aquatic nematode (about the size of microworms or smaller), really a worm, not an eel. They are found naturally appearing in vats of vinegar. They make excellent food for fry of nearly all species of aquarium fish. Their advantages over microworms is that they are slightly smaller and they live longer in the aquarium. Their disadvantage is the somewhat more complicated harvesting methods that are required.
(copied and pasted from
www.petfish.net same with the micro worm above)
pic from
www.carolina.com
Red worms...
Red worms, also called "Red Wigglers", are considered by many to be the best,"all around", bait. They will catch most all game fish world wide and will catch them when other baits and lures let you down.
copies from
www.klpoultryfarm.safeshopper.com
pic from
www.cityfarmer.org
The only difference in the fruit flies that I can find is size
pic taken from
www.livefoodcultures.com
D. melanogaster on the left and D. hydei on the right...the
scale is the same
I have fed my smaller vfts the flightless fruit flies and it worked out just fine you can find them at any old pet store realy at least places like pet smart and pet co. The others I don't think I would worry about or use. I deffinately wouldn't buy them from where I looked they just sell way too many and I would have no idea what to do with them. Plus they just seem too tiny. If you are up for suggestions crickets are good too if you get the smaller ones.