Are they both the same age, from the same litter, same generation etc?

I have 2 Tonks my blue male is a 2nd Gen and is more burmese in his looks (because he is an early generation) but the affectionate side of him is applicable to both Siamese and Burmese.
My brown female is a 5th Gen and is neither like a burmese or siamese in looks - she is a tonk. She is cuddly when she wants and can be very aloof when she feels like it too - it is just because she is female. I have always been told if you want an affectionate cuddly cat to go for a neuter male as they are much softer in nature than the females.

I think the biggest thing is that you need to look at them as Tonks and not at more like a siamese or more like a burmese.

I think if you want another kitten then maybe you need to go and see a litter of each - Tonkinese, Burmese and Siamese and then make your judgement based on the personality of the kitten you see.

Please post some piccies of them when you get a chance, I would love to see them. xx