Tamarack and Eastern Hemlock are different trees. Tamarack, aka Larch, loses its needles in the fall and regrows them in the spring, like the OP wrote about his tree. Eastern Hemlock (like all hemlocks) is evergreen - it keeps lots of needles all year round, although like all conifers it does drop each needle after a year or two, but never goes bare. In fact, a healthy hemlock should look more or less uniformly thick and green year round. Tamarack grows cones and is related to pines, spruces, hemlocks, and so it is a conifer, but it is a deciduous conifer, a bit different from the usual evergreen conifers.
Tamarack is one of the better conifers for firewood, higher in BTUs than most conifers.