GFCI and AFCI cover different aspects of safety. GFCI/AFCI together, of course, covers both.
- GFCI - Ground Fault Circuit Interrupter
GFCI watches hot and neutral (or with a double breaker, both hots and neutral) for an imbalance. Any imbalance must be going somewhere that it shouldn't, which could be through a person, which can be dangerous and even fatal.
GFCI can be as part of a circuit breaker to protect an entire circuit. It can also be at a receptacle to protect either that receptacle or that receptacle and everything after it in the circuit. It can also be provide GFCI protection only, without a receptacle, to protect everything after it in a circuit. Each method has advantages and disadvantages. Generally speaking, the electrical code does not care where you put it as long as key locations are protected. Historically GFCI has been needed for kitchens and bathrooms, but has been gradually expanded to additional areas such as outdoor receptacles, laundry rooms, garages, etc. GFCI is almost always least expensive when added as a receptacle replacement rather than a breaker replacement.
- AFCI - Arc Fault Circuit Interrupter
AFCI watches for the telltale signs of an arc. An arc is generally an indication of faulty wiring or appliances. Unfortunately, AFCI is very susceptible (compared to GFCI) to false alarms (nuisance trips with no actual problem causing them), so generally it is not added except where required by code. For example, GFCI is definitely, in my opinion (and my electrician's opinion), for bathrooms even when you are not changing anything else, while code generally requires it only for new circuits. On the other hand, AFCI, while ironically most useful for old wiring (because old wiring is more likely to have worn out insulation and other lurking problems), is generally only added for new circuits as required by code.
Because AFCI protects the wiring itself (from rodents gnawing insulation, loose connections to receptacles, etc.), it provides the most protection when installed as a AFCI/circuit breaker or installed very close to the panel. So on a new panel that generally means AFCI/circuit breaker.
Michigan is currently using the 2017 NEC. So any requirements for new circuits are based on the 2017 NEC, plus any local amendments. As I understand it, the 2017 NEC requires GFCI or AFCI in a lot of rooms. So that is your starting point for any new circuits. For any existing circuits, generally speaking you do not need to add AFCI or GFCI if you are not adding any new receptacles - i.e., if you simply replace existing receptacles (for grounding or aesthetics or just because they wore out) then you are OK but for anything new check to see if you need AFCI or GFCI.
A panel replacement with no real circuit changes may or may not require adding GFCI and/or AFCI for existing circuits. That depends on your jurisdiction and, possibly, on the inspector.