Hello Jayro,
Ford called the blue canister a fuel vapor storage canister and has a charcoal-type material inside. The rubber line from it attaches to a metal line that goes to the fuel tank and a fuel vapor valve on the top of the tank. The corrugated hose connects to a stub on the side of the air cleaner. The canister stores fuel vapor from the tank, and when the engine is started, the vapor is pulled through the air cleaner into the combustion chamber, where it is burnt.
The '71-72 canister is shorter, making the '73 version a one-year-only part. Ford installed it on full-size Ford, Gran Torino, Mustang, Maverick, Thunderbird, Bronco, E, and F100-350 series trucks. The '74 emissions and vapor recovery requirements had changed, so the vapor recovery canister was changed to comply with the new regs.
I know these many years later, many of our '71-3s have non-stock intakes, carburetors, air cleaners, etc. If your '73 is still running the original production installed configuration, I would leave the vapor recovery system intact. Since that is how these tanks vent on our vehicles, there is the possibility of raw gas fumes being emitted into an enclosed area such as a garage. There are some members here who have experienced just that. But, your car, your decision, just my opinion.
The black canister is an AC vacuum reservoir. It ensures that all the blend doors and vacuum-operated valves continue to operate correctly when the engine is in a low vacuum range, such as when experiencing moderate or heavy acceleration. If there was no reservoir, the air would default to the defroster ducts every time you accelerated.
The picture below is the vapor recovery canister and the AC vacuum reservoir on a '73 Mach 1.