There are two differences between male and female that actually affect the gameplay.

1. New female player gets 50 gp more gold.

birth.c
822:	/* She charmed the banker into it! -CJS- */
823:	/* She slept with the banker.. :) -GDH-  */
824:	if (!p_ptr->male) gold += 50;

2. Female players can't be attacked with the knee MA technique.

cmd1.c
2129:				if (ma_ptr->effect == MA_KNEE)
2130:				{
2131:					if (q_ptr->male)
2132:					{
2133:						msg_format(Ind, "You hit %s in the groin with your knee!", q_ptr->name);
2134:						special_effect = MA_KNEE;
2135:					}
2136:					else
2137:						msg_format(Ind, ma_ptr->desc, q_ptr->name);
2138:				}