Simply put... the PC version was made by a completely different studio, Gearbox (you might know them for Borderlands series, Brothers in Arms trilogy, Half Life Expansion Packs and several poorly done PC ports outsourced to them in early 2000s).

They simply totally botched up the PC version, mostly because of very idiotic alterations to engine that broke it even further, poor design decisions and leaving out entire levels that actually were in console versions.

The console version is miles better as it was done by Eurocom, the studio that made World is not Enough 64 and later on went to make Bond games for Activision when they took over the license. It has more levels than PC version, better and more open level design, it has driving sections, hell even some extra weapons... You were missing out on a lot when you were playing the inferior Gearbox's PC version. It was even being developed for a much longer time compared to the PC build.