Well Blogpost is a contextual link that will add more value than a link stacked up with others So if we have a PR3 blogpost is a lot better than a pr3 blogroll
Also what makes a difference is how high up the page the link is. If you have the same link on both your blogroll and your blogpost, whichever is nearest the top of the page (whichever google sees first) is the one that will count.