I saw a few articles about them time to time but don't know the real differences between them except what they do. Mind explaining their pros and cons?

Think of a freelancer as doing your normal job ... except you decide the work, hours and location. If you worked as an accountant for ACME Co and then you decided to freelance, you instead might get paid for by the job by multiple clients while working at home in your pajamas.

An entrepreneur puts something at risk. You use capital -- whether saved up or borrowed -- in an attempt to earn money.

I would also say the mindset is very different...entrepreneurs usually start out new business ideas without knowing if they are going to pan out, whereas freelancers just decide to work at their profession and be their own bosses.

Kind of like creating a job for yourself vs creating a new business

The pro of being an entrepreneur is a great earning potential, as your company could be worth millions some day whereas a freelancer earning ability will be tied directly to how many hours he/she works.

I totally agree with fortunecookie. And I would like to add that Entrepreneurs look more on the long term goals as compared to Freelancers

Having worked for a few years as a freelancer, I'd say there's also unlimited earning potential (one of my colleagues was earning $125K/year as a freelancer), but the reality for most freelancers is that unless they have established relationships with a few reliable clients who will give them steady work, more of your time as a freelancer is spent looking for work than actually doing it.

Plus you have to remember that if you take a vacation you have to consider not only the money you spent on your vacation but also the lost income because you weren't working.

Another big difference is that as a freelancer you are not your own boss: your clients are the bosses, so you actually have multiple bosses. As an entrepreneur you are conceivably your own boss, although you're still beholden to other people such as your investors/shareholders and your clients/customers. But you're closer to being your own boss as an entrepreneur than you are as a freelancer.