The confusion here are that you think sfp and "ethernet" are different things, they are not. Layer 2 ports can be either copper or fiber, both can use different speed, all in Megabit, copper 10/100/1000/10000, fiber 10/100/1000/10000/25000/40000/100000. Copper ports are cheaper and therefore often used on pc and servers, also the length of a copper cable can't be longer than 100 meters. For fiber the length is depending on the sfp type, is it a led or is it a laser, it can be a low power laser or high power laser, those can go up to 40 km probably longer, I have however not used sfp that reaches over 40 km.
For the differentiation between those 2 routers, use different vlans in the switches. For ports connecting different switches use trunk that carries both vlans. If communication is needed between the vlans, I suggest that both routers have ip in each vlan, can be done with the concept of subinterfaces.