All three are quite different.
HC is a proper stem plant with leaves in a vertical form, very similar to it's larger cousin, Hemianthus micranthemoides. It can become bushy like glosso and under good conditions displays creeping properties.
Glosso is classified as a creeping shoot plant, as multiple shoots often are born on a single stem. It can also be treated as a stemplant, since the stem can be cut and the individual plantlets preserved.
Marsilea is classified as a creeping shoot plant but it is also classified as a fern with a proper rhizome. New "stems" emerge from the terminal point of a rhizome, in a fashion similar to anubias. Cutting the rhizome into individual plantlets is not advised unless the plantlets are developed enough to have roots and their own terminal point which develops into their own rhizome. Again, similar to an anubia.
I have used Marsilea as a ground cover without CO2.
Good luck with your glosso, I found it kind of messy, but a great plant to work with.
llj