1 - Free Standing or an Attached type of structure?
This question is the first and best way to start distinguishing between these outdoor structures. If your project is freestanding, then it is either a pergola or patio cover. A patio cover can also be attached like an arbor (we’ll go into that difference in question two). Arbors will have posts or columns on one side and be connected to a home/building on the other side. This can be a point of confusion because many blogs, images, and descriptions refer to arbors as being freestanding arches or gateways to a garden or backyard. Some municipalities might require a structure to be attached.
2 - Rafters or a Truss Roof?
Pergolas and arbors use posts connected by joists and rafters for shade and stability, but those rafters don't keep rain or the elements out. It is an open-air type of roof structure.
3- Size of the structure -
This is sort of a trick question: there are no size guidelines differentiating arbors, pergolas, and patio covers. All three structures can be small or expansive based on what you want.
4 - What type of building material is to be used.
5 - Any type of top canopy covering. Today people may want to be look a rustic pergola but still may want to cover with wood, metal or a ploy type of materials.
6 - The color of stain / sealer / paint
7- Cobels and Rafter Tail ends details (Pergola, Arbors)
You won't have to worry about anything, except maybe getting your guests to leave!