I have noticed that submissions in '0' pr directories approves your link faster and even ,sometimes, no email confirmation links are sent.. but high pr directories they take time in approving your link and are sometimes no-follow.. I want to confirm about the difference in backlinks generated by these two types of submissions????
PR 0 directories are often new. They generally have smaller queues of pending submissions, so they can approve them faster. But, new directory owners may also get lazy and approve everything which is something you don't generally want. High PR directories, as a rule, get far more submissions, because so many are still blinding chasing the green. It's going to take them longer to go through the queues. No-follow directories, to me, are a waste of time to submit to. If a site is not worth linking to fully, it shouldn't be accepted in the first place. The real issue with directory submission is not the PR on the homepage or even the interior pages - it's the quality of the site. Many of the high PR directories have categories 60, 80, even 100 pages deep. So what if you have a listing on a high PR directory if your listing is over 100 clicks away from the homepage - think the search engines are even going to find it? Look for quality - all listings in the right categories, no keyword-filled titles or descriptions, categories that are full and broad of subject, etc. Forget PR and worry about the other stuff and you'll see a far greater return from your submissions.
New directories approve much more faster, because they have less listing to review. To encourage more submission, usually they will giving fast approval. If a directories only have few listing, it impress that it is not a good directories. High PR directories could receive few hundred to thousand submission a day, it sure take more time for them to review it. They receive quantity submission, so they can filter it and listed quality submission only. To avoid spamming, high PR site will implement nofollow tag. In addition, some of the directories purposely not approve free listing, so that user will subscribe to their pay listing.