Serial Garbage collector is a stop the world GC which stops application thread from running during both minor and major collection. Serial Garbage collector can be enabled using JVM option -XX:UseSerialGC and it's designed for Java application which doesn't have pause time requirement and has client configuration.
The Serial Garbage collector also defaulted GC in JDK 1.4 before ergonomics was introduced in JDK 1.5. Serial GC is most suited for small applications with fewer threads while throughput GG is more suited for large applications. On the other hand Throughput garbage collector is a parallel collector where minor and major collection happens in parallel taking full advantage of all the system resources available like multiple processors.
Though both major and minor collection runs on stop-the-world fashion and introduced pause in the application. Throughput Garbage collector can be enable using -XX:UseParallelGC or -XX:UseOldParallelGC.
