1) User Interface: My mother is using Nokia 3 and father Nokia 6 in India.
Incoming call is displayed always red background in Nokia 6 by default.
In contrast, Nokia 3 UI incoming call uses red colour for spam call.
Even though N 6 got early OS updates it lacks much needed one facility of UI.
2) Real duel sim facility: N3 got dedicated slotes for 2 sims and 1 for micro SD.
N6 got hybrid sim slot. Either use 2 sim or 1 sim and 1 SD.
I wasn't aware of this difference in the software. Are the two phones using different versions of Android? In fact it could actually be the phone app which is the problem, and this mainly depends on Google, not HMD.
I agree with you about the SIM slot problem, I wish HMD would just do separate memory card and dual-SIM slots.
@madbilly: Problem of UI is now solved. It happen due to UI based update rolled out in Nokia 3 first and then at least after a month updated to N6. I always follow monthly update for both phones.
Thanks for the feedback, good to hear it kind of fixed itself.