
Besides the fact that both can fly!

Answer: they're both 
jet-propelled!
(Air-Man's wings are balloons!
They don't flap like 
Hawkman, 
Birdman, or other avian-themed characters!)
 When ornithologist Claude Stevens was brutally murdered by criminals with an unbreakable alibi, his son Drake decided to avenge him by becoming a masked vigilante.
Using a jet-pack of his own design along with wing-shaped balloons for maneuverability and lift, Drake created an appropriately bird-themed secret identity as 
Air-Man to work outside the law for justice!
Air-Man caught the murderers, and decided to continue battling evil wherever he found it in the pages of 
Keen Detective Funnies and 
Detective Eye Comics!
On the other hand, Cal Martin and Doris Dalton were scientists who used their jet-packs as 
RocketMan and 
Rocket Girl almost on a whim, and found they enjoyed crimefighting, so they kept at it for several years!
They appeared in the back pages of the entire run of 
Scoop Comics, but never made the cover spot!
When 
Scoop was cancelled, they moved to 
Punch Comics where 
Rocket Girl finally got a solo cover, but 
RocketMan never did!
When their publisher went out of business, another company picked up the rights but re-named them 
Zip-Jets, since the abandoned "RocketMan" trademark had been taken over by Republic Pictures for their otherwise unrelated leather-jacketed flying serial hero!
Two issues of 
Zip-Jet, reprinting their 
Scoop & 
Punch stories came out before their new publisher also went kaput!
The duo made a final appearance in a one-shot titled 
Atomic Comics, but whether it was new or reprinted material is unknown, since the issue we scanned for our kool kollectibles was slabbed! ;-(
All three characters have re-appeared in minor roles in Alex Ross' 
Project SuperPowers, with hints of bigger things to come!
We at 
Atomic Kommie Comics™ have revived 
both Air-Man (both 
Keen Detective Funnies appearances) AND literally ALL 
RocketMan & Rocket Girl aka the 
Zip-Jets cover appearances, as part of our 
Lost Heroes of the Golden Age of Comics™ line, on t-shirts, messenger bags, mugs and other kool kollectibles!
So, next time someone says "Look, up in the sky...", it might not be who you think...
And don't forget to buy the NEWEST 
Project SuperPowers comics including
...Black Terror,
 Death Defying 'Devil,
 Masquerade, and 
Project SuperPowers "Volume 2", as well as 
Savage Dragon!
 ON SALE NOW!