Distinguishing Fischer and Schrock compounds

Heya,

just looking at my lecture notes from an organometallics lecture and was wondering how to distinguish compounds wrt Fischer and Schrock only by looking at the given structure.
I was given

(CO)5Cr=C(OMe)(Me) as "obviously" a Fischer type carbene and (Cp)2(Me)Ta=CH2 as a Schrock-type.

Due to the elements position in the periodic table the Fischer = late TM and Schrock= early TM theory cannot really apply here.
So, is the only thing to look out for the R groups (ie Fischer = heteroatom, Schrock =alkyl) or is there a better way to distinguish those compounds?

Thanks a lot for your help!!!