These days... the major difference is cost and availability.
The .45LC is a much bigger brass cartridge... thus it costs more simply based on material used.
Also, the .45ACP is produced much more frequently, so cost comes down on that simply because of supply.
All though with the popularity of the 1911 shooters out there... .45LC might be easier now days to actually find.
but... like I said, they make more .45ACP annualy for all the military and police use, so there is simply far more of that on the market.
If you are a hand reloader, .45LC is gonna simply have a higher starting cost because of the brass.