Not quite the same as Tarmac SL3. Looks like Allez has a little more stack height.

Same wheelbase, same steerer head and seatpost angles. Around 5mm difference in standover height, TT length and reach.

Tarmac SL4 has shorter head tube for sure-- in a 58cm frame it's 15mm shorter than Tarmaz SL3 and Allez. That's the main reason I would say the Allez OSBB frame is more like a Tarmac SL3.