Great tip from Mark Shaw in his blog on the use of the @reply and the @mention on Twitter!
Over to him…
“What is the difference between these 2 sentences…….and believe me… There is a huge difference in their outcome…
Exhibit 1…

Exhibit 2…

The Answer is…
Exhibit 1 is called an @reply as the Twitter message begins with an @twitterusername. The people that will automatically see that message are… You (because you sent it), the recipient who you @replied AND anyone that follows both you and them. So its not private, but in reality as many peeps dont follow both people in a conversation, they WILL NOT SEE AN @REPLY
Exhibit 2 is called an @mention as the @twitterusername is anywhere but at the beginning of the message. So who sees this automatically? You (because you sent it), the recipient because they were mentioned, BUT now also ALL OF YOUR FOLLOWERS.”
As Mark points out, there’s a huge difference in terms of numbers of those who might see your tweet. When you @reply someone automatically the 2 of you will see that message and anyone else that follows both of you – that could be a few, none or thousands. But, if you @mention their name instead, then 2 of you automatically see that message as well as all of your followers, regardless of whether they follow the other person or not.
So think it through before you use one or the other.
If you are telling your mate what time you will meet them in the pub, then an @reply is absolutely all that is needed. If however, you are replying with something of value –  answering technical questions, giving out a link that may be useful to many, or perhaps demonstrating your specialist knowledge and positioning yourself as an expert, then you may be better served by using the @mention. Use wisely though – we’ve all heard the remarks from the disparagers… “Twitter is full of people telling you what they had for lunch”. Be sure not to give them any ammunition with inappropriate use of your @ key in the wrong place!
You can read Mark Shaw’s full article here
If you need help with managing your Twitter account let us know – always happy to point you in the right direction 🙂