Our preschool says it has a 'tie-up' with a big school for nursery. What does that usually mean?

At the parents' orientation, our son's preschool mentioned a tie-up with a large school nearby and said children 'usually get through' for nursery there. Nothing more specific was said, and the school wasn't named in writing. I'd like to understand what this tends to mean in practice before it influences any decision. Is it a guaranteed seat, a priority interview, a shared syllabus, or mostly a sales line? I'd be grateful to hear from parents whose children went through such an arrangement, and I'll treat second-hand accounts as second-hand.