More than the final outline
Names such as squash, round, pin and swallow describe the end of the board, but the width and volume leading into the tail are equally important. Two squash tails can behave differently if one is much wider.
Wider tails
More tail area can create lift and help a board generate speed in weaker waves. The board may feel lively, though control can depend on rails, fins and how much pressure the surfer can apply.
Narrower tails
A narrower tail can sit deeper in the water and provide control in faster or more powerful waves. It may require more wave energy and better positioning to keep speed.
Read the combination
Tail shape is one part of the system. Rocker controls the curve, rails influence engagement and fins add direction and hold. Compare the whole rear third of the board rather than buying from a tail icon.