Derby are going through their second straight season in League One and they are eyeing promotion to the Championship this season.
Portsmouth are also determined to get back to the Championship this season after spending more than five years in League One.
Evans believes that Derby County and Portsmouth are both giants in the division but pointed out that taking everything else and the size of the Pride Park into consideration, the Rams are bigger than Pompey.
The Stevenage boss hailed Derby as the biggest club in League One and termed his side’s win over the Rams at the weekend a marvellous moment for his club.
When asked about Stevenage’s win over Derby County, Evans told Stevenage’s media: ”Yes, it was a marvellous one wasn’t it?
“They are the giants of League One.
“I have seen some written press saying, ‘are they bigger than Portsmouth?’ I don’t know.
“They are two giants, aren’t they?
“They are a massive club, but if you take the stadium and everything into consideration, it probably means they are the leading club in League One.”
Derby are currently in seventh in the league table and Portsmouth are at the top of League One.
