is a specific kind of: bum, do-nothing, idler, layabout, loafer.

is a broader term that covers: lingerer, loiterer | plodder, slowcoach, slowpoke, stick-in-the-mud | potterer, putterer | straggler, strayer.

derivation: dawdle, fall back, fall behind, lag | dally, dawdle | dawdle, linger | drag, drop back, drop behind, get behind, hang back, trail | shack, trail | dilatory, laggard, pokey, poky.