The difference between "Anticlastic" and "Synclastic" can be measured in the curvature.

ANTICLASTIC   K < 0 (minus)
Formactive structures are tensioned through the curvature of the surface e.g.rep. as U/V or warp/weft.The surface is therefore tensioned if the product of the principal curvatures is negative (- K) so called "anticlastic".

SYNCLASTIC    k > 0 (positive)
Only air-supported structures should have a positive curvature (K>0) what is called "synclasitc".

DEVELOPABLE    K = 0 (zero)
Objects like a zylinder or boxes do not have a curvature (K) and can be unrolled without any distortion.

NOTE:
Please note that there are shapes like the "double sphere" over the "bar-bell ground plan" with anticlastic and synclasic areas (Frei Otto "Spannweiten p. 90)

"Gaussian Curvature" (K) that is the product of the principal curvatures: