Agreed. Speed metal is just traditional heavy metal played faster. Thrash requires a very specific riffing style, i.e. the "thrash riff" with its palm muting, jagged rawness, and possible punk influence.
Power metal is speed metal with a distinct European, classical, or faux-operatic overtone. Add some thrash riffs, and it becomes power/thrash. Add more punk, more rawness, it becomes thrash. Helloween's Walls of Jericho was a speed metal album. Keeper of the Seven Keys Pt.1 was a power metal album. Helstar is power/thrash, as most American power metal bands tend to be.
More speed metal? Exciter, Accept, Judas Priest, Motorhead, early Agent Steel, early Overkill, Iron Maiden (also NWOBHM), etc.