Differences between import_style=commonjs+dts vs import_style=typescript

By comparing the output of these two import styles, it seems there are some differences. Mainly commonjs+dts seems to require grpc requests to use callback while typescript allows for promises. I would like to use commonjs+dts but I want the output to be consistent with what we would get if we just compiled the typescript file. Can someone explain why there are differences and if these anyway to make these two more similar in regards to types and features.