We correlate the notion of n-isoclinism of finite groups, introduced by J. C. Bioch in 1976, with the relative n-th nilpotency degree, recently studied in literature. We characterize also all the pairs which are isoclinic with (C,D_8) via the relative commutativity degree d(C,D_8), where C is a cyclic maximal subgroup of D_8. A final conjecture is opened for the groups with few nontrivial values of d(C,G).
