I just thought that lstopo deserved to get a mention.
What it does: it simply shows the topology of your CPU, which means it shows not only logical cores and physical cores, but also the different levels of caches as well as how PCI devices are connected.
Simply run lstopo and you get something like this (Ryzen 9 3900X):
You can zoom in and out with “+” and “-”.
This tool has a lot of different command line options, see manpage for more details.
(Cool feature: supports ASCII output when running lstopo --of ascii)