Coverage is the same. The only difference is a network provider will direct bill GeoBlue. In most cases, with any other provider you will have to pay the bill and file a claim for reimbursement. Unfortunately, in most cases people will not end up being treated by a network provider.
By the way, with an annual GeoBlue "Trekker" plan, in addition to direct billing, the deductible is waived when you use a network provider. There is no deductible with the single trip Voyageur Choice plan.