How to interpret diode diagrams
Most semiconductor device processes have a few doping levels available for the designer to use. Instead of working with the actual concentrations, it's easier to work with p+ vs. p to say it has more acceptors. N+ will similarly have more donors.

It's very common in semiconductor physics to go even further and use: n--, n-, n, n+, n++ or p--, p-, p, p+, p++ to talk about doped regions.

Eg. We could be working with an extremely P lowly doped substrate (p--) in which you have a pwell (p-) and the contact to the pwell is made with a highly doped diffusion region (p+).