Which kind of FALLACY does it fall under

This can also be an example of equivocation . The kind of eating cows do of grass differs from the kind of eating humans do of grass. Also, the grass the cows eat is substantially different from the kind humans eat (i.e., grass that is broken down to nutrients and absorbed in the meat).

P1) A is Y

P2) B is X

C) Therefore B is Y

That is a non sequitur, and this Venn Diagram demonstrates it.