There is no clear consensus on who had bigger arms between Arnold Schwarzenegger and Hulk Hogan. Both men were incredibly muscular and had large arms, but it is hard to say definitively who was larger.
One factor that may have contributed to Hogan's perceived size advantage is the fact that he often wore tight shirts that showed off his muscles, while Schwarzenegger tended to wear looser clothing. In addition, Hogan often flexed his arms in photos and interviews, while Schwarzenegger did not do this as often.
However, there are also many photos and videos of both men with their arms exposed, and it is clear that they both had extremely large and well-developed muscles. Ultimately, it is impossible to say definitively who had bigger arms between these two legendary bodybuilders.