Ultimately,
@Imperious is right in one thing: We could use the Royal Tour to talk to both Borros and Jeyne. The argument could, in theory, also be applied to Jeyne.
However
Jeyne at the wedding is basically a two birds with one stone sort of deal. She is a perfect dancing partner for the Defiant option. With Borros we could just talk, t here is nothing specific to the wedding, and we can in fact also do that on the Royal Tour. With Jeyne, there is in fact something specific to the wedding, an opportunity to grasp.
As well as what Azel said. The Baratheons love hunting. They would probably be more relaxed on a hunting trip than on a wedding, and we might enjoy it, too. Whereas I see no equivalent option for Jeyne Arryn in the Vale; probably we would just talk to her there, and we can also do that here, combining it with a dance.
Basically, no, the Royal Tour is not fully equivalent to the Wedding, and Jeyne is not fully equivalent to Borros.