In this study, we employ first-principles calculations to explore the structural and electronic properties of monoclinic Al2O3/Ga2O3 superlattices with varied layer thickness and to perform a comparative analysis with (AlxGa1-x)(2)O-3 alloys. Our investigation examines the lattice constants and electronic energy bandgaps of both the superlattice structures and alloys across different Al concentrations, shedding light on the intricate relationship between composition and electronic properties. The analysis on electronic properties reveals that as the number of Al2O3 monolayers in the Al2O3/Ga2O3 superlattice rises from 2 to 6 monolayers, the bandgap correspondingly expands from 5.29 to 6.43 eV. The band alignment between monoclinic Al2O3 and Ga2O3 exhibits a type-II band alignment. The conduction and valence band offsets between the bulk material and Al2O3/Ga2O3 superlattice varies with change in the number of Al2O3 monolayers. Our study gives a deeper insight into the properties of the Al2O3/Ga2O3 superlattice and suggests a solution to the Al-phase separation issue in (AlxGa1-x)(2)O-3 alloys for advanced semiconductor device applications.