LTD are more in the mid-entry level with their instruments more in the 500$ range.
You will usually see an ESP model and an ltd copy at half the price.
While this is absolutely right for guitars, the bass side of ESP/LTD is more complicated than that.
As of now (reference: their website + some quick Thomann lookups), there are only three ESP bass series: the Vintage 4 (passive, 4-string P-bass with Seymour Duncan Basslines PJ pickups), the Surveyor (a more modern take on a P shape, with active electronics and P-MM EMG pickups, available in 4 and 5-string models) and the Phoenix II (a Thunderbird with EMGs). Now all three are high-end, Japan-made instruments that retail for around 1500 euros (and I sure wouldn't mind owning a Surveyor 5 if I was in the market for a modern-sounding instrument -- aesthetically, it has a nice, understated, dare I say Lakland-like quality).
LTDs, on the other hand, are made in Korea (I think -- it may have changed recently) and thus cheaper, but you'll notice that they offer a much wider range of instruments: 10 different series (including the aforementioned 3), at prices that scale from less than 200 euros to around 1000-1200. The looks also scale from trying-too-hard-to-be-metal (I'm a metalhead, but I just can't stand the look of pointy, clearly-impossible to play sitting down instruments), to all-around gorgeous (the spalted maple finish on the B41x's is yum!). Also, ESP/LTD's only 6-string basses are LTDs (the B and D series are available as 4, 5 and 6ers).
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So make no mistake -- although "ESP" is a foolproof mark of price and/or quality, just because a bass says LTD on the headstock is in no way indicative of cheapness or crappiness. In that regard, I think ESP is closer to Ibanez than Fender or Warwick: ESP-branded basses are the equivalent of the Ibanez Prestige line (always top-notch and Japan-made, but which currently features only SRs, and ATKs starting this NAMM) and LTD is everything else from the entry-level meh to the higher-end of the middle-end, with a lot of possible "sidegrades" and series/options not available in the flagship line.