imagine company of heroes and red orchestra together as FPS.
welcome to HLL xD
instead like PS HLL has "real frontlines" because there are multiple sectors providing one of the 3 resources. Every sector which is connected to your side can be capped.
instead fighting along a line of points like in PS you fight on separate points at once. At some points are squads which defend the own ones while others are trying to get new ones.
Battles are also more intense. I played the closed alpha where only infantry was playable and I enjoyed it more than PS now.
EDIT:
here are some pics: