If you were to make a list of everyone you know personally, you might have a long list. On the other hand, if you were to divide those names into two columns, friends vs. acquaintances, the friends' column would be significantly shorter.
The definition
In conversation, the sentence "A friend told me" or "A friend gave me" rolls so much easier off the tongue than "An acquaintance said." By definition, a friend is someone whom you've known for some time, like and trust. An acquaintance you know, but with whom you haven't formed a close relationship.
Time factor
If a friend is someone you've known for some time, does that mean an acquaintance automatically turns into a friend after a certain period of time? Not necessarily. There are people you can know for years without ever making the transition to trusted friend.
Friend vs. acquaintance
If you're not quite sure whether someone is a friend or an acquaintance, ask yourself the following questions:
Common ground
With a friend, you usually have something in common. You might have different backgrounds, different careers and different interests, but somewhere along the line you found common ground. With acquaintances, you might not even know about or be interested in many aspects of their lives.
Making a difference
The leap from acquaintance to friend usually happens spontaneously. You might have known the person for a month or a year, and suddenly the connection you have formed puts them in the "friend" category. Perhaps an incident occurred where this person showed you he or she was trustworthy and special, and the bond was formed.
Everybody likes to have lots of friends, or at least seem like they do to appear popular and loved. After all, having so many friends is a testimony that you are a social and likeable person. But if you don't really understand the difference between friends vs. acquaintances, you might end up disappointed and embarrassed.