You can distinguish a weed that looks like lettuce from the real deal by closely observing leaf shape, texture, and growth patterns. Weeds may have a similar broadleaf structure but often display subtle differences like a variance in the edges of the leaves, a slightly different shade of green, or an unusual pattern of veining. Pay attention also to flowering patterns, as many weeds will bolt and produce flowers, unlike lettuce which remains leaf-focused unless it’s bolting.