Besides differences in words, what other challenge do Europeans face in communicating with each other? They use two different alphabets
People in the United States speak mostly English
Europe's population is about double the size of the United States
Most of the people in Europe do not want to learn another language

They use two different alphabets

Explanation:

In Europe, there are various languages, as most of the countries have their official languages spoken. The largest groups of languages from which other European languages come from are Germanic languages, Romantic languages, and Slavic languages, but there are numerous others (Baltic, Greek, Uralic, Celtic, etc.)

Besides the fact that these languages are all widely different in vocabulary, they also don’t all share the same alphabet.

Germanic and Romantic languages all use the Latin alphabet, yet some of the Slavic languages use Cyrillic. Among those that have Cyrillic as the primary alphabet is the Russian language which has the largest number of speakers in Europe. Czech, Polish and Slovak languages are examples of Slavic languages that use the Latin alphabet, while other ones that use Cyrillic are Serbian, Ukrainian, Belarus, Bulgarian, etc. While the Greek alphabet is sometimes called Cyrillic, it has both Latin and Cyrillic letters and is widely different that Slavic Cyrillic.