which one is better? Thanks in advance.

This is really a question for the newbie board, but...here goes.  I'm a member of both sites and each has its strong points.
P411 is easier to join because they have an 800#.  Last I checked D-C did not, though I hope that changes.  So if you don't have the perfect criteria for membership you can talk to someone at P411 and work out alternate means.  P411 is located in Canada, so US LE can never get to their computers.  Their listings clearly show which girls are newbie friendly while D-C does not.  Their search function is good.
D-C is just as credible with most providers.  Their strong suit is their Calendar function.  If you select your "favorites," the Calendar will show where they are geographically.  It's a nice, quick way to search.
Bottom line: if you're just starting out I'd join P411 first, especially if you have any issues with your info and/or don't want to provide employment info.  I like using both because of their complementary ways to search and because some providers prefer one over the other so you're totally covered with both.

If you think you will be a lifetime monger, DC offers lifetime membership for 124.95. P411 only offers annual membership at 89. Plus, it will go up to 129 on March 1. It will also start offering 6-month, 3-month and 1-month memberships to 'casual  hobbyists'.

In my experience, it seems more providers use P411. I have made quite a few dates through it but never through DC. Also, P411 website is more low-key while the DC website is too revealing for my taste.

P411 and date-check are similar but different services.  I like them both.

I could go into detail but it might take too long.

My experience is that a REAL hobbyist needs both, they have different features and the more verification the better.

To correct a prior post, p411 does offer lifetime membership after 2 years of good behavior.

In my opinion, the only benefit of date-check is they are cheaper and have the lifetime membership option. I am a lifetime member there, but If I didn't have the lifetime membership at DC, I would not be renewing.

1) Date-check has profiles for ladies who retired years ago. P411 will remove a profile and put a lady's status as inactive if she doesn't check in at least once every 2 months.

2) P411 is not cluttered with ads.

3) P411 has much better search features.

4) P411 has a better PM feature, and the pre screening, or appointment request form is nice.

5) Ladies on P411 can only check your profile if you give them your ID number. On date-check anyone can check your profile if you are signed on. You have control over who you allow to see your profile.

6) So far all the ladies I have seen who are on date-check, are also on P411, and all the ladies I have interest in seeing who are on date-check are on P411, so I have no need to belong to both (that may differ in different regions of the country).

7) P411 is more user friendly and much easier to navigate.

8) All the stuff Natasha mentioned.

I know dome folks who have P411  lifetime memberships that were offerred to them in the past, but there is no lifetime membership now. With the recent price increase they just offerred current members, the opportunity to purchase "as many years if membership as they would like" at the old rate fir a limited time. If there was currently a lifetime membership, why would they not be offerring a lifetime membership instead?

Also a few months back (prior to the price increase anniuncement) they had a deal where you pay for two years and get one year free. Again, no lifetime option.