Chuckle Lots of Different Thoughts on this one allow me to answer the best that I can.
First the Difference between the Seal and the Marines most of your are right in saying that the Seals are the Navy's SF but then you also have to remember that General Gray CMC answered the army like this when asked if Marine Recon would be Part of SOCOM "The Marine Corps as a whole is a special Force" now believe it or not it some ways its is true the Marines do specialize thier training to fit missions that the army would have a hard time doing with its conventional forces here is a list of Missions that a baic SOC qualled MEU has been tested and evaluated on
Marine Expeditionary Units are capable of executing missions with 6 hours of notice. The versatility and rapid response of a MEU make it the choice of the Unified Commanders for contingency operations arising within their Areas Of Responsibility (AOR). Each MEU earns qualification as Special Operations Capable (SOC) prior to its 6-month sea deployment. Each MEU trains for the "3-block war," that is contingencies arising across the conflict spectrum. From humanitarian assistance to full-scale warfare, MEUs are trained and prepared for the missions that may arise in the world's "hot spots." Listed below are the missions of a MEU and the spectrum of conflict in which a MEU is trained and has proven capable to operate
Operations Other Than War
Peace Operations
Peacekeeping
Peace Enforcement
Joint/Combined/Instruction Team
Humanitarian Assistance/Disaster Relief
Security Operations
Noncombatant Evacuation Operations
Reinforcement Operations
Amphibious Operations
Amphibious Demonstration
Amphibious Raid
Amphibious Assault
Amphibious Withdrawal
Supporting Operations
Tactical Deception Operations
Intelligence, Surveillance, Reconnaissance (ISR)
Military Operations in Urban Terrain
Reconnaissance and Surveillance
Fire Support Planning, Coordination, Control in a Joint/Combined Environment
Counter Intelligence
Airfield/Port Seizure
Show of Force Operations
Expeditionary Airfield Operations
Terminal Guidance Operations
Joint Task Force Enabling Operations
Sniping Operations
Direct Action
In-Extremis Hostage Recovery
Seizure/Recovery of Offshore Energy Facilities
Specialized Demolition Operations
Tactical Recovery of Aircraft and Personnel
Seizure/Recovery of Selected Personnel or Material
Counter Proliferation of Weapons of Mass Destruction
Visit, Board, Search and Seizure of Vessels
Provide Command, Control, Communications, and Computers (C4)
Limited Expeditionary Airfield Operations
Enhanced Urban Operations
Enabling Operations
Employ Non-lethal Weapons
Information Operations
Anti-Terrorism
Rapid Response Planning Process (R2P2)
The training difference is easy the Seals are trained in guerilla and small unit tactics. Maries are taught squad and fire team tactics more often or not the term "movement to contact" comes into play here Seals like to be quiet and unseen if they can be. The Marines Have Recon to do basically a similiar job as the Seals Training is differ because its the Navy's way to train seals and the Marine way for Marines.
Now here is the easiest way to compare the 2 The Marine Corps as a whole can be considered your modern day Invasion force we secure a beachhead for the follow on forces (IE the Army) but in recent years our ability as a war fighting unit to rapidly deploy anywhere in the world on such a large scale has made us the first responders for problems arising world wide. I am not knocking the Army but they are big heavy and slow when it comes to getting someplace once they are the ground and moving they are wonderfull assest for a Ground commander.
Now the Army is seen largely as an Occupying force which is why they are now in Iraq for example playing UN police.
Another Huge difference is the fact that the Marine Corps Carries all its on Basic warfare elements with it we are the total package so to say
Ground
Air
Support
Arty
all of it is rolled up nice and neat in a package that is used to working together.
The SF thing the Marines have finally stepped into the Realm of SOCOM with Mar Det 1 though there is still a lot to be figured out for one Marines do not like to be commanded by anyone other then Marines and for two the giving up of trained men and equipment for them to be used as they see fit by another branch is not something that sits well in the day and age of budget and manning cuts.
I hope I have cleared some of this up
They whole elite thing I think comes from the fact that Seals are part of SOCOM and the Marines are Well Marines thats they only title we will ever need!!!
SemperFi