Who's Right? Leasehold or Freehold?

My friend Rohan and I have been going back and forth on this question. We both did our internships at the same law firm, and I'm sure it'll be a useful question for CUET PG Law aspirants.

Question: A property is sold by a leaseholder with a remaining lease term of 20 years. The buyer is unaware of a restriction in the deed that prohibits sublease. Who has the higher title, the seller or the buyer?

Rohan says: "Easy, seller has a higher title. The buyer is aware of the restriction and therefore cannot claim a better title."

But I think: "Hold on! The buyer bought a property, not the lease itself. The seller's interest is in the lease, not the freehold. The buyer has an interest in the freehold and has a valid title for that."

Who's right? What's the law? Help us settle this!