Typically the skillsets for a sales engineer/consultant and a post-sales engineer/implementation consult are overlapping but different.
In many organizations the pre-sales engineers are there to answer technical questions during the sales process - "will this integrate with X?" "can I solve Y problem?" "how many concurrent users does this support?"
The post-sales consulting team is there to actually wire up the integration with X, solve Y problem, and tune the performance to support Z concurrent users.
The challenge with a hybrid role is balancing zooming out to being aware of the strategic "making the sale" parts of being a sales engineer to the super low-level nuts and bolts connecting things together of post-sale consulting.
In either case clear communication and listening are the key skills I would work on. The ability to actually hear what a customer wants, and clearly communicate that you understand what they want and can deliver it is a difference maker on either side of a sale.
I've worked in both roles, both are rewarding and frustrating for their own reasons - good luck!