Q: “In surround sound, isn’t an LFE channel the same as a subwoofer channel?”
A: Actually, LFE and a subwoofer are two very different things. Typically, the term subwoofer refers to a speaker that reproduces very low-frequency information that the main channel speakers (however many there are) are incapable of effectively reproducing, or at least augments them such that low-frequency sounds normally found on the main audio channels are directed to the subwoofer speaker for added punch in the low range. In this way, a subwoofer acts as a complement to extend the range of the main speakers, which may find it difficult, if not impossible, to reproduce these low frequencies in the quantities needed. The LFE is a separate channel that has its own, dedicated track in the audio production. The LFE channel is often specifically produced with low-frequency information exclusive to it. Content producers create emphatic sound effects for it, such as, crashes, gunshots, and such. Ultimately the purpose is not all that different from the goals of conventional subwoofers, and subwoofer speakers are quite often used for playback of LFE information, which is typically bandwidth limited to lower frequencies best suited for subs. It’s just important to understand the distinction between the two.