The XT M771-10 cassette has its three biggest cogs on one aluminum spider, the next three on another spider, the next two loose with spacers and the top two with built-in spacers.
The SLX HG81 cassette has the three biggest cogs on one aluminum spider, the next six as a riveted stack, and the top two with built-in spacers.
The Deore HG50 version has no aluminum spider and the bottom 8 cogs are a riveted stack.
XTR has titanium bits.
There are definitely visible differences in level of fit and finish between a Deore and XT, but I haven't had an SLX in hand.
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Genesis 49:16-17
"Well, well!" said Holmes, impatiently. "A good cyclist does not need a high road. The moor is intersected with paths and the moon is at the full."