Okay, I understand. You're saying your local utility (POCO), which follows PG&E's Greenbook Section 1.14D (regarding service entrance conductors), is indicating that the two situations in your diagram necessitate different sizing for the service entrance conductors.Without the diagram I am just guessing here are some reasons why there would be different service entrance conductor size.
1. Service Disconnect Location

If one is outdoors and the other is indoors, that affects the length the service entrance conductors have to be.2.

Demand Load Calculation

The POCO will likely make different assumptions about the connected load based on the nature of the buildings being served. For example, a commercial building will have a higher demand load, and diversity factor, than a dwelling.3.

Available Short-Circuit Current

If one is closer to the transformer, than the other, the AIC rating may need to be upgraded, which in turn would affect the conductors needed for the overcurrent protection.

General Information* PG&E Greenbook (Section 1.14D - Service Entrance Conductors)

This section of the Greenbook outlines PG&E's requirements and specifications for service entrance conductors. It includes details on conductor sizing, types, installation methods, and termination requirements. The goal is to ensure safe and reliable connection of the customer's electrical system to the utility's grid.

To Get More Specific Advice

To give you more precise feedback, please provide the diagram or additional information from the utility company on the reasons why different conductor sizing would be needed. Flag for review