Ё is a distinct letter. You can find ё in children's literature (ёжик, ёлочка, самолёт), but almost all authors will have e replacing it in the business, academic and journalistic literature. This exchange is found only on the letter.
Ё is pronounced like yo in the English word Yoga. Remember: the accent always falls on ё.
Now the problem of the letter ё occurs among all Russian editors, writers and authors. Some scientists believe that we should use ё in the literature, others believe that it should be replaced by е. For example, Arkady Milchin argues that ё is used in literature only if the meaning of the word with е is unclear, such as with "все - everybody" and "всё - everything". There are different meanings in the words with е and ё. For example, Тема is a topic and Тёма is diminutive-hypocoristic name of Артём.
A magazine "За рулём" was published in 1928. It used the letter e in the word "рулем" until 1956. Then, in the years 1956-1975 it used the letter ё. From 1975 to nowadays it used the letter е in the name of the magazine. You can look through the photos.