As to OP question I saw all types of little differences like that while selling batteries, some were odd. I use 96 series rather than 40, the 96 a bit smaller and guarantees the battery can swap into my Contour as well that way. 40 is a bit longer IIRC. My old measurements say so anyway.
Some confusion there too, not all AGM batteries use gel type electrolyte, some use conventional type water-like acid that pours into the battery just like lead acid ones do. Can make for charging difficulties when you really don't know what type battery it is, AGM charge differently from lead acid. They may well show a bit more cranking amp too.