TACLET is a deployable, law-enforcement team, consisting of law enforcement
detachments (LEDETS) Their primary mission is counter-drug law enforcement. While counter-drug law enforcement is one of the LEDETs' largest missions, they have played an important role in military maritime interdiction and maritime security operations, conducting boardings and assisting in training U.S. and allied boarding teams. TACLET South continually deploy teams to the Caribbean, Pacific Ocean and Persian Gulf with deployments lasting 45 to 90 days. At a minimum, each member can expect to be deployed for 185 days of the year, normally on a Navy
ship. You also have PACTACLET which is located in Southern California.
Most LEDETS have approximately 11 billets where MSST's have around 75.
MSST teams are also deployable but mainly stay within their AOR. MSST are staffed to maximize effectiveness executing Port, Waterways, and Coastal Security (PWCS) operations (enforce security zones, port state control boardings, protection of military outloads and major marine events, augment shoreside security at waterfront facilities, detect WMD weapons/agents, and participate in port level antiterrorism exercises). Maritime interdiction and law enforcement. MSST teams commonly are involved with;
Vertical Insertion (commonly referred to as Fast Roping)
Search and Rescue (limited)
Underwater Port Security
Canine Handling Teams (Explosive detection)
Tactical Boat Operations
Hook and Climb
Non-compliant boarding operations
Either one depending on the Billet you are trying to fill depends on what the required qualifications are. I hope I answered atleast part of your question. If you have any more specific questions let me know!