The 1010 has a rack-size breakout box that contains all your 1/4" TRS balanced analog input/output jacks, MIDI, and word clock. This breakout box has a power supply and contains the actual A/D/A converters, lowering the noise floor and making them more accurate than converters on PCI cards (this is actually very subtle in most cases). The breakout box cable is about 10' long so you have a lot of placement options for your rig.
The 1010LT does not have a breakout box, it has a bunch of dangly wires that hang out the back of the card. The analog I/O is all done via unbalanced RCA connectors, which means you have to get a bunch of stupid adapters or make special cables. All of the converters are right on the PCI card. They also bundled a couple mic preamps with the LT that are also right on the PCI card. I'm sure they are of usable quality.
If you are seriously on a budget, then the 1010LT is probably the wise choice. If you can score a cheap 1010 though, it's definately the better product.
The only real drawback to the 1010 is that all the connectors are on the back of the rack unit. This makes it fine for fixed installations, but it's awkward if you don't have a patchbay. I don't think this detracts from the product itself enough to warrant not considering it though. I just have mine mounted backwards

Oh, and SPDIF on the 1010 is on the back of the PCI card which kinda sucks but is easily worked around.
Slackmaster 2000