You are setting up Session Replay, and would like to know how you can tell the difference between a replay that was sampled due to a replay sample rate and a replay that was sampled manually with start().

If you want to only record replays manually, then you have most likely set (docs):

Therefore, when you are viewing the recorded replay, you can see in the tags tab that these values are set to 0, and therefore determine that the replay is definitelly manually recorded.

However, if you have set a nonzero sample rate for your replays, manually stop a replay that was being recorded automatically, and then start recording another one manually, there will be no way to distinguish which one was recorded manually.