This thread reminds me of a joke I picked up a while back from a High School teacher of mine who was with 19th SF. It speaks to the aforementioned differences between Rangers and SF.
Ranger Vs Special Forces Organizations
The Chief of Staff of the Army asked his Sergeant Major, who was both Ranger and Special Forces qualified, which organization he would recommend to form a new anti-terrorist unit. The Sergeant Major responded to the General's question with this parable: If there were a hijacked DELTA 747 being held by terrorists along with its passengers and crew and an anti-terrorist unit formed either by the Rangers or the Special Forces was given a Rescue/Recovery Mission; what would you expect to happen?
Ranger Option
Forces/Equipment Committed: If the Rangers went in, they would send a Ranger company of 120 men with standard army issue equipment.
Mission Preparation: The Ranger Company First Sergeant would conduct a Hair Cut and boots inspection.
Infiltration Technique: They would insist on double timing, in company formation, wearing their combat equipment, and singing Jody cadence all the way to the site of the hijacked aircraft.
Actions in the Objective Area: Once they arrived, the Ranger company would establish their ORP, put out security elements, conduct a leaders recon, reapply their face cammo, and conduct final preparations for Actions on the OBJ.
Results of Operation: The Rescue/Recovery Operation would be completed within one hour; all of the terrorists and most of the passengers would have been killed, the Rangers would have sustained light casualties and the DELTA 747 probably would be worthless to anyone except a scrap dealer.
Special Forces Option
Forces/Equipment Committed: If Special Forces went in, they would send only a 12 man team (all SF units are divisible by 12 for some arcane historical reason) however, due to the exotic nature of their equipment the SF Team would cost the same amount to deploy as the Ranger Company.
Mission Preparation: The SF Team Sergeant would request relaxed dress and grooming standards for the team.
Infiltration Technique: The team would insist on separate travel orders with Max Per Diem, and each would get to the site of the hijacking by his own means. At least one third of the team would insist on jumping in.
Actions in the Objective Area: Once they arrived , the SF Team would cache their military uniforms, establish a Team Room, use their illegal Team Fund to stock the unauthorized Team Room Bar, check out the situation by talking to the locals, and have a Team Meeting to discuss the merits of the terrorists' cause.
Results of Operation: The Rescue/Recovery Operation would take two weeks to complete and by that time all of the terrorists would have been killed, (and would have left signed confessions); and most of the passengers would be ruined psychologically for the remainder of their lives. The DELTA 747 would be essentially unharmed, the team would have taken no casualties but would have used up, lost or stolen all the "high speed" equipment issued to them.
Not entirely accurate, but entertaining nonetheless.
Based on the stories from aforementioned teacher, SF seems to be able to choose weapons from the armory based on personal preference and mission, but not personal weapons. On the same line of thought, I have a friend who claims to have brought his personal Barrett M82 to Iraq in 2004 when he deployed as part of 10th Mountain Division. I don't believe him.