The top one is definitely a species of Pterygoplichthys as it has at least 13 dorsal fin rays- my guess would be that it's a pale sailfin plec (Pterygoplichthys gibbiceps, sometimes referred to as Glyptoperichthys gibbiceps) but there are some similar species.
The bottom one looks like one of the varieties of common plecs- identifying this to species would be really difficult- we'd need to see how many dorsal fin rays it has even to get it to genus (possibly another Pterygoplichthys, most likely P. pardalis, if it has 12 or more rays, or possibly a species of Hypostomus if there are less than 10 rays). The mouth looks wrong for Pterygoplichthys pardalis though.
Pic 1 correctly identified
Pic 2 P. paradalis - the mouth is correct when in the middle of action. I have spent a great deal of time observing mine when on the front glass. The mouth does take on subtle shape changes both when eating and when locked to the glass.
I have a gibbiceps, paradalis, and BN's (both albino and regular).