I don’t think the two are equivalent… both are fruit, but apples and oranges?

notice indicates the severity of the message logged – if you have a logging threshold of info, for example, debug messages won’t show up but notices will. The syslog protocol defines the available severities with numerical codes (see section 6.2.1 table 2 on page 11). A “notice” is described as “normal but significant condition” and it lives right between “info” and “warning”.

I’m not an expert on this, but Logger sends messages buffered to specific targets whereas IO.inspect is pegged to STDOUT. Sometimes I have to remember this e.g. if I start a process in one iex session and when I join it via another Terminal window. IO.inspect may be visible in one and not the other.

Credo has such warning.

Very much this. IO.inspect is the printf of elixir, while Logger is a means of logging to configurable backends with multiple capabilities besides raw string logs, …. The stuff you’d pull in a library for in many languages.