Active area is the area in which the transistors will be made ,in proccess with well implant options ,n+ implante usually used to form the n well and p+ the p well.It is a concept against the passive area used to isolating ,passivating ,etc.
n+ and p+ is a concept of dopant concentration .Many areas and steps using the n+ or p+ diffusion and implantation,such as the source ,drain ,the Vt adjustment implantation ,the body contact. The n+ p+ concentraion can varies from e+17 to e+21,all these concentration can be called n+ and p+.