for the specs. Why exactly the difference? I'd just be guessing so I won't.
You can also look at that sticker under your hood, the specs are printed there for your Teg. Your valve adjustment specs are there too BTW.
Stock plug for a GSR B18C1 is:
1.3 mm (0.051 in)
1.3mm or .051"
NGK spark plug number, last two digits are the gap in millimeters.
Other B-series engines have 1.1mm gaps. GS-R motors are an exception.
And 1.0-1.1 or (.039-.043in) for the B18C5.
[edited because I fucked up and read his question wrong]