There are slots in the top and side of the cup pocket. A few reviews on the website mention that they found the edges of the cup pockets scratchy but I wore this two days in a row to an indoor waterpark and for a paddle boarding lesson and found the bra very comfortable and not at all scratchy. I thought the fit was very similar to a regular Energy bra and probably could not tell the difference if someone zapped the bra onto my body and said guess which one you are wearing.
You can also see that a regular Energy Bra has a coolmax liner, whereas the H20 has swim material as a liner.
The bra cups are one of the biggest differences between the two bras. For some reason the H20 is a U-shape. Maybe it migrates less than the other shape. I never wear the other cups in my bras but I did put them in for the H20.
You can see the strap construction is a little different between the two bras.
The fabric content is a little different.