When referring to a person, plain means rather ordinary features.
Ugly refers to a variety of factors perceived as unattractive to a certain viewer. The concept of ugly varies quite widely among cultures and social classes. The single factor that sociologists could identify when large numbers of people were quizzed on which photographs were of ugly people was that feature imbalance on the face was often identified as ugly.
you're ugly
you are just plain ugly.
latitude
Ugly, plain, tasteless.
A plain is a flat grassy area and a prairie is a type of plain. It is not as flat but with little bumps.
Both are between hills and mountains
She is not overly beautiful, nor ugly- just plain Jane.
To make a difference between ugly and hot people.
There is no difference between plain flour and all-purpose flour. They are one and the same. All-purpose (plain) flour does not contain the salt and baking soda that self-rising flour has.
The difference between plain white flower and whole meal flour is that whole meal flour is a little denser. Also plain white flour is bleached so it looks white.
A plain is flat land no high hills or mountains.A valley is an area with more hills, mountains, and high land with river and/or lakes running through.There is a difference between a valley and a plain. The difference is that the valley goes up and down, and the plain is flat and large.
Desert has no significant vegetation. Coastal plain usually has lots of vegetation.