[Shin Densetsu]

Basically, the ROTF line featured some designs which were IIRC, meant for Classics 2.0 in 2008 but did not make it until ROTF, like Bludgeon. By the same token, Seaspray from HFTD IMHO, fits more in Classics than movie.

HFTD is primarily movie styling. Generations is primarily Classics styling. Both lines are merging into Reveal the Shield.

Power Core Combiners is its own line.

The Universe exclusive repaints(like Countdown and Bruticus) at TRU are seen as "close enough" by Hasbro to fit in with Universe/Classics 2.0.

Armada was a step back in articulation and was a gimmick line. So were Energon and Cybertron, but Cybertron was known for the return to full articulation for most figures, and some fans who despised Armada/Energon like Cybertron, like me. I loved Cybertron. Cybertron Prime is one of the BEST modern Prime figures ever made.