Generally speaking, a plug valve and a ball valve may absolve the same function (fluid shut-off). The main differences are:

Plug valves are more economical than ball valves, generally, due to their simpler design

Plug valves are less prone to contamination by debris, and accumulation of dirt in the interstitial spaces, compared to ball valves (an issue that is frequently faced by ball valves, due to the spaces existing between the sphere and the body of the valve)

Ball valves require more maintenance than plug valves, especially after planned or unplanned plant shut-downs

Plug valves have a full port design, without pressure drops, ball valves may be reduced or full port (a full port ball valve would be heavier and bulkier than a plug valve of the same size)

In general, plug valves are good alternatives to ball valves, even if ball valves are still considered industry standard for shut-off operations at least in the oil & gas industry.