Well Trainmasters and Baby Trainmasters looked a lot like each other !! The H-16-66 went into production first, about a year ahead of the H-24-66 Trainmaster. When the Trainmaster debuted, FM changed the H-16-66 so it had as many interchangeable parts with the H-24-66 as possible. Early H-16-66's were a little different - rounded cab windows etc. - but from 1953 on they were almost identical except that the Baby TM was about 3-1/2' shorter.
I've seen several instances from back in the day of railmags or books misidentifying the CNW's or Milwaukee's H-16-66's as "Trainmasters"!!
I guess in general the roadswitcher and switcher lines from FM did share at least one common trait, the very tall hoods!! They were needed because the opposed piston diesel motors stood a lot taller than EMD or other builder's motors did.