I’m still learning but need some help here. Multiple times I have seen an exterior 200 amp service disconnect close to the service meter. Then in the interior at the main breaker panel a second 200 amp service disconnect. Will the second panel be considered a subpanel where the neutral/ground should be separated and the neutral isolated?
You only have one main panel. It is typically at the meter. In some areas the meter socket may be outside but the main panel inside. Your first disconnect is your MAIN. Anything after it is a sub-panel. Some AHJ’s require a second disconnect to disconnect a panel completely depending on the distance from the main. There are some exceptions in the case of detached structures but if in the same structure it is a sub-panel and neutrals and grounds should be isolated.
The breaker outside is the service disconnect or service equipment. Regardless of whether it is a panel or a single disconnect, it is the “Service Equipment” and gets bonded.
The grounded/neutral conductors for everything on the load side (downstream) of the service equipment should be isolated.
Avoid using the term “main panel” as it creates confusion. The panel inside is a distribution panel or distribution equipment. It is on the load side of the service equipment so the grounded conductor should be isolated in order to prevent “objectionable current” from flowing through the enclosure where it can present a shock hazard.