You're right, LE stands for limited edition. The same models without the "LE" simply means it's not limited edition, which could mean it's Combat Grade (CG), a one off from a show, a custom shop piece, etc.
The limited edition versions of a knife have different specs from the CGs (lower-cost production models). They are not one-offs however, because their specs are set and they are put into limited regular production. Their specs may also differ dramatically from the CGs such that the use and feeling of a LE might be completely different from the CG's. The most common difference so far is that LEs have a satin finish and CGs are coated. LEs also usually have a serial number.