Some codes differentiate between the different types of socket weld fittings, and some do not. For the codes that make a distinction:

Type 8 is a socket weld with a smooth transition of the weld leg parallel with the pipe axis (achieved by grinding and finishing the weld). In other words, a very gradual concave weld surface to minimize the stress intensification at the socket connection. The default SIF here is 1.3, unless the applicable code specifically addresses this configuration.

Type 9 is an unfinished socket weld. The default SIF here is 2.1, unless the applicable code specifically addresses this configuration.