Aamir Khan was already a huge name a much ,much bigger star than SRK and 4 years his senior
Not a rank newcomer like SRK after Deewana
He already had Qayamat Se Qayamat Tak
Qsqt halter the action hero era of Amitabh Bachchan and Dharmendra
Which was copied by the likes of Anil Kapoor and Mithun Chakraborty.
Dil which outgrossed Ghayal Sunny Deol who was the biggest superstar of the era
Dil Hai Ki Manta Nahi
&
Jo Jeeta Wohi Sikandar
Even SRK said he watched Qsqt in college
SRK movies like Raju Bangaya Gentleman
And
Kabhi Haan Kabhi Naa
Were Aamir Khan rejects even Juhi Chawla when asked about the newcomer for Raju Bangaya Gentleman was said that he's like Aamir Khan
After the huge flop which was Lamhe Yash Chopra and Aamir Khan worked together in Parampara
Yash Chopra's first movie after Deewar which produced by an outside producer
Deewar by Gulshan Rai
And Parampara by Feroz Nadiadwala
Aamir Khan already a young superstar wanted a join narration with Sunny Deol
He was not okay with the fact that Sunny Deol would beat the shit out of him like he did too SRK in the movie he wanted a equal fight and Juhi Chawla killing his character.
He even said he didn't reject Darr he was removed from it.
According to me Aamir Khan was a conventionally handsome person
Who was considered the future of Bollywood
Came from a very celebrated film family
had the option to reject someone like Yash Chopra
Who was struggling at the time Darr was his first big hit
after Trishul in 1978
Hell Aamir Khan even said no to the likes of Manmohan Desai who was unargulbaly bollywood's biggest filmmaker
Now SRK was in a different place altogether
He came in via TV
Had no film family backing only came to Bollywood to escape the sadness of his mother's death
Wasn't considered a conventionally handsome ,tall , strong bodied action hero like Sanjay Dutt and Akshay Kumar
Neither was considered a good looking romantic hero like Salman Khan
Had just started his career Was doing films like Deewana
Chamatkar
Dil Ashna Hai
With stalwarts like Jeetendra
and Rishi Kapoor etc
Was willing to experiment with an anti hero thriller movie like Baazigar
Had no qualms against playing a stalker villain in the traditional 90s
SRK even said too Guddu Dhanoa his first producer of Deewana if my 6 films don't work I'll go back to Delhi
But like Aamir Khan he also rejected big people like Feroz Khan
Plus SRK was a huge fan of Yash Chopra
The first movie he ever watched was Joshila directed by Yash Chopra himself
& Readily agreed for Darr
Which created a long lasting partnership between SRK and yrf which till date stands
Hence I hope you understand that both Aamir Khan and Shah Rukh Khan were at different places of there career.