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In practical terms, the difference is negligible.
In a signed network, the similarity is defined as (1+cor)/2; in a signed hybrid the similarity equals the correlation if the correlation is positive and zero otherwise (it is called hybrid because it is a hybrid of weighted and unweighted networks). The similarity is raised to a power which is usually twice as big in signed networks than it is in hybrid networks. For correlations near 1, ( (1+cor)/2 )^(2*beta) approximately equals cor^beta, and for low correlations both adjacencies are near zero.