A huge amount of CS is algorithms and data structures. My undergrad degree also required two semesters of learning how a computer works from a logic gate level

A huge amount of CS is algorithms and data structures. My undergrad degree also required two semesters of learning how a computer works from a logic gate level upwards, culminating with writing a simple pipelined CPU in Verilog. After three years I had a pretty good understanding from both the high level (algorithms) and the low level (caches, etc). CS programs vary, but basically all of them give you the tools needed to write efficient code. They generally don't teach you much about software "engineering", though, which remains a chaotic mess of a field.