Carob galactomannan and Soya galactomannan both have a 1,4-beta-D-mannan backbone and galactose as alpha-1,6-linked single units. Carob has about 23% galactose and soy has 32%. Both are hydrolysed rapidly and to a high degree by beta-manannase. The distribution of galactosyl residues in these two galactomannans is quite different, refer to the two papers below:
McCleary, B. V. (1979). Enzymic hydrolysis, fine structure, and gelling interaction of legume seed Dgalacto-D-mannans. Carbohydrate Research, 71, 205-230.
McCleary, B. V., Dea, I. C. M., Clark, A. H. and Rees, D. A. (1985). The fine structures of guar and carob galactomannans. Carbohydrate Research, 139, 237-260.