You can find more details here:
http://www.5g-bullets.com/5G%20in%20Bullets%20-%20LTE_Idle_Mode_Sample.pdf
There 4 types of phones config A, B,C and D as in the table from the link above.
There is another group of Operators who shows 4G for HSPA+ and 5G while using LTE 4CA.
I.e. they display the logo they need without following the above table.
Mostly it will be TAC based classification.