Do we all have the same number of veins/arteries

or do fatter people have more and skinnier less?

It depends on size, mostly muscle. Fat cells don't need as much blood to maintain as muscle cells do, so the more muscle someone has, the more veins they grow. Basically the body grows as many veins as it needs in order to pump blood efficiently to all areas of the body. If someone exercises a lot, they will eventually start to grow more veins to maintain blood supply to all areas. If a vein becomes clogged or blocked, a new vein can grow to bypass the blockage. But just because someone is fat doesn't mean they have more veins. Most likely, a "fat" person is more sedentary, so they can pump blood through their body just fine without having to grow lots more veins.

Noone has the same number or distance of veins/arteries as another person. Veins and arteries are used to supply blood to all the cells in a body. The more cells there are in a body, the more veins, arteries, and capillaries are needed to sustain that body. The average sized body has about 90000km vessels.

For every pound of fat, more blood vessels are needed. So, to answer your question, fatter people do end up with more blood vessels than skinny people.

no and yes.

the main veins and arteries are basically the same. more so with arteries, veins are highly variable.
However, the smaller ones are all somewhat different in each person.
Additionally, someone who is fatter will require more veins and arteries to supply/drain the fat of blood.

What an interesting question!........Perhaps we all have more or less the same number. All major arteries and veins might be certain in number because we have only certain number of organs.