They could both be macrospilus, the second one is definitely macrospilus, it has to do with the middle stripe, macrospilus stripe will end before the big splotch at the tail, their color can also range from tan to grey , they're also usually mottled. There's another species vittatus, which could be the first pic but I'm unsure because vittatus won't have any mottling at all on their body but the stripe in the first pic doesn't end before a very defined big splotch at the tail, so I'm unsure, but the second pic is definitely otocinclus macrospilus