Ethernet cables are defined by their standard eg CAT 5, CAT 6, etc. The increasingly posh cables tend to be faster (higher throughput), have a higher signal to noise ratio (fewer packets dropped) and lower crosstalk between the insulated twisted pairs making up the cable. They tend to be thicker, with more insulation.
Within a standard there are differences. Cables using stranded wire tends to be more flexible (so less likely to break) and is often used as patch cable whereas solid wire tends to be be used for fixed runs. The solid stuff is cheaper.
Also, cheap ethernet cable from a dubious source may claim to meet a standard but doesn't due to skimping on the composition of the wire itself (aluminium/copper alloy rather than pure copper), thinner wire, etc.
My recommendation would be to go with a name you can trust rather than a cheapy off ebay.