Basically they get their power from a different source and thus have different range of power and abilities.
Electromagnetic suit-
"The Guardian battlesuit is able generate, and manipulate a powerful electromagnetic field. That field forms an exoskeleton around guardian augmenting his strength [3.5 tons]. This electromagnetic energy can also be used to form a force-field around Guardian. The suit also enables the wearer to fly at the speed of sound (mach 1-2). The suite is also able to channel blasts of electromagnetic plasma channeled through the gauntlets. These blasts can equal the force of 250 lbs of TNT. Since the power of the suite is derived from the electromagnetic forces of the Earth, Guardian is able to manipulate the gravitational force around his body. Effectively guardian is able to freeze himself in place relative to Earths rotation. This accomplishes near instantaneous transportation along a strait line." This suit also had sonics capable of taking out Klaw and Wonderman, as well as Flares and an acid blast.
Geothermal suit-
"Heather was able to use it to cause eruptions of steam and lava from her hands. She was also able to cause the earth to erupt volcanically. " Able to press 25-75 tons".
"Heather Hudson wore a battlesuit of unknown origins and largely unquantified abilities while a field operative with Alpha Flight. The suit enabled her to fly, and allowed her to "tap geothermal energies." Using the suit she has produced steam blasts, lava blasts, created a small volcano and produced cool water with the suit. Hudson was still in the process of learning her battlesuit's capabilities when Alpha Flight v2 was cancelled. "
Good lord I can't believe majority of the threads here people are saying Alpha FLight wins. I thought there would be some doubters, good to see some people see just how good my fav team is