Yeah, Mark's article was awesome!
Olympic is pretty easy to figure out in the broadstrokes, IMO. Like pictures of the Second Class Dining Saloon, galley, etc. The 1911 shipbuilder magazine primarily focuses on Olympic's construction, so that's helped me a lot to distinguish.
Its when there's a possibility it could be Titanic because there's photos near or similar to those known to be taken on Titanic.
For example, the A-Deck promenade on the two ships
This is Titanic's, on April 10th, 1912 (from my own files)
But this is Olympic's (wikimedia commons)
If you didn't know any better, you could think this was Titanic's promenade just further aft and earlier in the day