# Are there some similarities between J-coupling and j,j-coupling?

I'm a bit confused having heard two different terms in different lecture parts:

• J-coupling

There is the J-coupling (= indirect dipole dipole coupling = scalar coupling) which arises from a hyperfine interaction between the nuclei and the interaction. The J-coupling is a coupling between the two nuclear spins of two nuclei (e.g. a C-H bond). Because of the Pauli principle the two binding electrons are anti-parallel located so the nuclear spins $I_1$ and $I_2$ also have an anti-parallel nuclear spin.

• j,j-coupling

There is as well the jj-coupling (= spin orbit coupling) which describes the coupling of the different $j_i$. This coupling scheme is valid for heavier atoms. (For leight atoms the ls-coupling is valid). In atoms with bigger nuclear charges, spin-orbit interactions are frequently as large as or larger than spin-spin interactions or orbit-orbit interactions. $\mathbf J = \sum_i \mathbf j_i = \sum_i (\boldsymbol{\ell}_i + \mathbf{s}_i).$ Wikipedia

I don't see any commonalities. Why is the term "J-coupling" similar to the term "j,j-coupling"?