Difference between 'friendlier' and 'more friendly'

[Trongtuyenvnbt]

Hi every one,
Could you help me to find the difference between these sentences.
1 Her father is friendlier than her mother.
2.Her father is more friendly than her mother.
Thanks a lot!

[HamburgEnglish]

happily - more happily - the most happily
friendly - more friendly- the most friendly

[Barb_D]

There's no difference. Some words don't take the "-er" ending, and need "more." Some can go either way. I don't object to either "friendlier" or "more friendly."