Twitter hashtags vs @ mentions

@mentions

@redoliveryan – @mentions are for talking to someone. These show up in your timeline, your followers see them, and they show up in your recipients @ mentions in-box, and people can search twitter for these.

To view tweets where people have mentioned you: login to twitter, click ‘home’ and then click ‘@mentions.’
Or go to search.twitter.com and search for @yourusername.

Examples:
You want to thank a customer: @redoliveryan thanks for your support.
You want to ask a question: @redoliveryan are title tags important?
You want to send a shout out: Shout out to @redoliveryan you rock!
You want to recommend something: @redolivedesign really did a great job on my site!
You want to mention people, and you want them to get it in their @ inbox: @redolivedesign and @redolivebrad did a great job.

#hashtags

#redoliveryan – #hashtags are for talking about something. These show up in your timeline, your followers see them, and people can search twitter for these.

To view hashtags of people talking about you or your industry, go to search.twitter.com and search #yourusername or #yourindustry.

Examples:
You are at a conference: #redoliveconf there will be a meet-up @dairyqueen in Sandy at 7pm on 08/07.
Another conference idea: Have conference attendees use a special conference hashtag, such as #redoliveconf, to comment or ask questions.
You want to participate in a trending topic: #myfavoritemovieis Dumb and Dumber. (If #myfavoritemoveis were trending). You can check for trending topics at search.twitter.com.
You want to talk about a company: #redolivedesign is the bomb!
You want to make up your own topic: If you want to follow my ideas, follow the hashtag #ryanideas

I hope this helps.