In 2008 right after SEI was formed I undertook a personal mission to familiarize as many ops and resorts as possible with just what SEI was. I sent out over 500 emails with our philosophy, standards, and history. You will not have any problems as our certs continue to be used around the world. We also have large and very active branches in Italy, Japan, and Korea.
Your SEI course will include skills and knowledge other courses do not including emergency deco procedures using the Navy Air Tables, Rescue skills that include how to deal with a panicked diver, surfacing a non responsive diver from depth, supporting a diver at the surface, and rescue tows while stripping gear and getting the person out of the water. These are mandatory according to standards and must be taught.
So yes there are differences as these are not included in most other OW courses. The basic course if taught according to standards is more comprehensive, takes longer, requires more pool and classroom time, and has items that other agency courses do not cover until the pro ranks. If they cover it at all.
The instructor is also free to add skills that he/she feels will be of benefit to you. I include a few blacked out and no mask skills since we dive in a lot of low vis conditions. He/she is also likely to add knowledge that is not in the book and is based again on his/her views of what is necessary and will make you a safer and more skilled diver.
And just an FYI, during my email marketing campaign I discovered that the card that many ops care about the most is your VISA or MASTERCARD. After the fall of the Soviet Union I was informed that a whole bunch of new cards appeared on the scene from former behind the Iron Curtain countries. Many ops will ask you to do a check out dive anyway and once they see you in the water there will be no doubts about your skills and knowledge. And if you want to dive in certain areas in Europe where choices are even more limited just ask your instructor to issue you a CMAS card as well as the SEI one. That one will give you no issues anywhere in the world.