1) Y= X1+ X1*X1+X2 + X1*X2 + (X2)*(X1*X1) i.e. adding not only the interaction with the low level X1 but also the interaction with the quadratic term X1*X1.
2) Y= X1+ X1*X1+X2 + X1*X2 i.e. just adding the interaction between X2 and the lower level of X1.

x1 is a continuous var whereas x2 is gender.

which is correct? or both are?