I think if Snowbarry were to be fulfilled on telly, it would differ a lot from Olicity in that it’s not simple fan wish fulfillment becoming canon especially with Caitlin Snow being an intersex werewolf (she got the shapeshifting part from being fused with a female wolf and Caitlin’s androgen insensitive).
In this scenario, Snowbarry becomes fulfilled in a really strange way with Caitlin impersonating both Iris West (Barry’s greatest love) and Captain Cold (Barry Allen’s foe) on separate occasions, which is saying. Almost as if these latter two actually matter a lot more in their historical relation to Barry Allen.
Not to mention it gives weird credence to the ‘Coldflash’ pairing. Caitlin is jealous of Iris to the point of impersonating her in seducing Barry Allen. So it’s Snowbarry becoming a thing, albeit not in a way fans expected it to be. But when it comes to impersonation, that’s when it differs from Olicity.
Not so much in Caitlin being the real Iris but that impersonating her deconstructs fan suspicions as well as why they made Iris black as she’s originally white. Olicity was straightforward fan service (pandering to fans), Snowbarry confuses and compounds fans if it happens.