Refernce cards will be very close, so if buying the FE cards, you can expect thermal throttling and similar performance.
As for AIB cards, ... No, they do not EVER hit the same clocks. The EVGA SC series has historically been a reference card with a better cooler.... same VRM, no additonal cooling for MOFSETS, VRM and as a result, their OCs are limited. The competition changes PC components and that's wahy the SC series can't match their OCs
OCs are affected by many things including:
the quality of the cooler
quality of PCB Componnets
what means of cooking on PCB
This is never made more obvious than in the tear down article below. Read the bottom third of pages 2 thru 4 and long before you get to the performance page, you will know how they rank in performance.
http://www.guru3d.com/articles_pages/msi_geforce_gtx_1070_gaming_x_review,30.html
You will note also that the EVGA 970 SC was defective in that 1 of the 3 heat pipes missed the GPU... after issuing a press release stating that was "by intent", they came back with the SSC which corrected the heat pipe issue but left all the other deficiencies noted in the article as is.
Note also it's not about maintaining the highest clock but maintaining the highest boost clock and the highest fps. You can have a higher OC on the core, but have a lower boost clock and lower fps because when under load, the card is cutting back via voltage, power or temp protection.
If all cards OC the same, why do we see this ?
https://www.techpowerup.com/reviews/MSI/GTX_980_Ti_Lightning/26.html
MSI GTX 980 Ti Lightning 1518 MHz 2090 MHz
Colorful iGame GTX 980 Ti 1432 MHz 2020 MHz
Palit GTX 980 Ti JetStream 1515 MHz 2100 MHz
ASUS GTX 980 Ti STRIX 1472 MHz 2070 MHz
ZOTAC GTX 980 Ti AMP! 1465 MHz 1990 MHz
MSI GTX 980 Ti Gaming 1507 MHz 2040 MHz
EVGA GTX 980 Ti SC+ 1491 MHz 1900 MHz
Gigabyte GTX 980 Ti G1 Gaming 1512 MHz 2100 MHz
GTX 980 Ti 1437 MHz 2070 MHz