"What's the big difference between WS-C2960S-48TS-L and WS-C2960S-48TS-S? What' the meaning of the -L and -S? "

In Cisco 2960 series switches,-L means LAN Base while -S means LAN Lite.To compare those two cisco 2960 switch, you can follow:

WS-C2960S-48TS-L is a Catalyst 2960S 48 GigE 4 x SFP LAN Base Switch ,which is an easy-to-use Layer 2 edge switch suits for enterprise, midmarket, and branch office networks with highly secure business operations, improved sustainability, borderless network experience and lower total cost of ownership.

WS-C2960S-48TS-S is a Catalyst 2960S 48 GigE 2 x SFP LAN Lite Switch ,which simplified from Lan Base software to Lan Lite for more adaptation if customers’ business is entry-level branch office or wiring closet networks, distinguish with Lan Base software for a more complex business requiring.