IC= Insulated can. Meaning it can have direct contact with insulation. Many IC's are also air tight. Meaning you wount have air comming in from a hot or cold attic thru the can vents.
TC= Thermo cutout, or is it thermo can. Meaning it has a over tempiture safty cut out switch. I think most incandesent cans for many years have these cut out switches. A TC can is not to be be placed in direct contact with insulation. What is it 6" minimum space from insulation. I would say TC's you need to keep more space from combustables as they leak out the hot air thru the vents. The plus side of TC's is they tend to allow higher wattages.