.

In respect to this, can I use spackle instead of wood filler?

I would use spackle personally. It doesn't shrink like joint compound and it dries very quickly. Wood filler is still the best option obviously but spackle works well if you're just going to paint it anyway.

Subsequently, question is, how do you fill outside nail holes? prime the bare nail/hole with oil primer. Then any type of exterior spackle or painter's oil putty will fill the void. A hard filler like bondo will be prone to pop out the next season when the nail moves again. A gel epoxy is a very costly but most permanent solution.

Additionally, is spackling waterproof?

Painters use caulk and spackling compound to fill gaps and holes, but that's about all these two materials have in common. Whereas caulk is a flexible coating that resists moisture, spackling compound dries hard and isn't water-resistant.

What is the difference between painters putty and spackle?

Painters putty vs spackle: Painters putty and spackle are very similar, but there is a difference. Painters putty is designed with painters in mind, whereas spackle is not designed just to be painted. Both can take each other's place if needed, but it's best to use painters putty if possible.