Finite simple groups of Lie type over a field of the same characteristic with the same prime graph

For a finite group G, let pi(G) be the set of prime divisors of its order, and let omega(G) be the set of orders of its elements. Define on pi(G) a graph with the following adjacency relation: distinct vertices r and s from pi(G) are adjacent if and only if rs is an element of omega (G). This graph is called the Grunberg-Kegel graph or prime graph of the group G and is denoted by GK(G). We prove that, if G and G(1) are nonisomorphic finite simple groups of Lie type over fields of orders q and q(1), respectively, of the same characteristic, then the graphs GK (G) and GK (G(1)) coincide if and only if either {G, G(1)} = {A(1)(8), A(2)(2)} or q = q(1) and the pair {G, G(1)} coincides with one of the pairs {B-n (q), C-n (q)} for odd q, {B-3(q), D-4(q)}, and {C-3(q), D-4(q)}.