-al:

SUFFIX:
Of, relating to, or characterized by: parental.

ETYMOLOGY:
Middle English, from Old French, from Latin -lis, adj. suff.

SUFFIX:
Action; process: retrieval.

ETYMOLOGY:
Middle English -aille, from Old French, from Latin -lia, from neuter pl. of -lis.

-ic

 
SUFFIX:
1. Of, relating to, or characterized by: seismic. 2. Having a valence higher than that of a specified element in compounds or ions named with adjectives ending in –ous: sulfuric acid. 3. One relating to or characterized by: academic.

ETYMOLOGY:
Middle English, from Old French -ique, from Latin -icus and from Greek -ikos.

(Note that one of -al's definitions IS verbal, in describing action or process.)