Specifically regarding MySQL, what is the difference between a thread and a process? The documentation seems to refer to them interchangeably at times, and it even throws in the term "session" too.
At the most basic level, the command to show threads includes the term
PROCESSLIST, as if a list of processes is a list of threads. (https://dev.mysql.com/doc/refman/5.6/en/show-processlist.html -- The first sentence says this list "shows which threads are running.") But then, in the
performance_schema.threads table, each thread there has its own unique
thread_id that is not the
ID returned from
SHOW [FULL] PROCESSLIST. Instead,
PROCESSLIST_ID is a foreign key to the PROCESSLIST (https://dev.mysql.com/doc/refman/5.6/en/threads-table.html). This leads me to believe that threads and processes are not the same thing.