what is the difference in this vs the low sodium one by the same company. It's similar price but a larger bottle. Any major difference?

I had looked this up before i bought. This one is double brewed. Meaning they start with an already brewed sauce and do it again. From their website: Low sodium: The traditional methods of its founding 200 years, soybeans, wheat, solar salt only as a raw material, in the rich natural, flavor components by our own way from brewed soy sauce that was slowly fermentation and aging in large cedar barrels, as it is, only the sodium chloride by 50 % cut was flavorful soy sauce. This one: “KINBUE SAISIKOMINAMASYOYU” was carefully made with soybeans and wheat carefully selected, using golden whipped soy sauce instead of salt water, squeezed moromi which was naturally fermented and matured as it is, It is very luxurious raw soy sauce. I bought both of them. I use the low sodium to cook with and general stuff, this one i use for dips and more special stuff. Like you would do with fancy oils vs cooking oils

Is this in a glass bottle?

Yes, this and the low sodium are both glass

Most fermented soy products including all forms of soy sauce contain MSG, which is produced naturally. Like salt, MSG is not inherently unhealthy, but the amount that is consumed.