More than meets the eye.

[Chesspiece_face]

There is no similarity. 'Similarity' implies that there is some small degree of difference— Jetfire is identical to the Robotech robots. Right down to the gun and the detachable armor/booster suite. You could even transform him part-way just as the Robotech machines did, throwing out their engine nacelles as legs and the arms out to fire the rifle while still bearing a resemblence to a fighter airframe.

Bear in mind that, in the show, the Transformer was known as Skyfire. For odd merchandising reasons, they simply took the Robotech model, slapped some Autobot decals on it, and sold it as Jetfire.

By the by, my Jetfire was one of the few that were spared from the screwdriver.

This was all because of american liscensing issues. The copywrite for the Macross Toys was only held in japan, thus allowing transformers to use the toy model for Jetfire. The copywrite for the image use in america, however, was liscensed to Harmony Gold when they released Robotech in america (Robotech being the amalgamation of the japanese series Super Dimensional Fortress Macross, Super Dimension Cavalry Southern Cross, and Genisis Climer Mospeada). Thus the reason that in the Transformers cartoon Jetfire was named Skyfire and had a different model. They couldn't use the image of the Macross Mecha.

Edit: Add Link; http://en.wikipedia.org/wiki/Jetfire