Question

which alcohol and carboxylic acid would produce benzyl isobutyrate by Fischer esterification? and which alcohol and carboxylic acid would produce isobutyl benzoate by fischer esterification?

I can't find anything about Fischer esterification specifically. But acids + alcohols produce esters.
Benzoic acid + isobutyl alcohol yields isobutyl bnzoate.
BzCOOH + HOCH2CH(CH3)2 ==> BzCOOCH2CH(CH3)2

isobutyric acid + benzyl alcohol yields benzyl isobutyrate.
(CH3)2CHCOOH + HOCH2Bz==>(CH3)2CHCOOCH2Bz

Again my references don't speak to a Fischer synthesis. I don't know if the above will be helpful or not.
Check my work!