They're equivalent in the sense that PlusCal, the pseudo-code-like language compiles to TLA+, the mathematical notation. The book Practical TLA+ teaches pretty

They're equivalent in the sense that PlusCal, the pseudo-code-like language compiles to TLA+, the mathematical notation. The book Practical TLA+ teaches pretty much only PlusCal. Eventually, though, to get the full power, even those who start with PlusCal will need to learn at least some TLA+.