Hi - I think someone pointed out it depends on the labor laws where you are working.
Making an assumption you are somewhere in the US, and even then the laws can be different by state...but making an assumption you are somewhere similar to where I have worked. My guess is the difference in your pay is because before you were a contract worker, you did not work for Coca-Cola, but were either an independent contractor or hired through and outside agency, your pay scale would be completely different than a full time employee. You get paid more hourly because you do not directly work for the company and therefore you do not get any benefits.
Once the company hired you on as a full time employee, they are (in most places at least that I am aware of) required by law to give you certain benefits and often times the company may provide greater benefits than required by law, things like health, dental, life insurance, disability both long and short, perhaps some sort of 401k or retirement benefits, vacation and holiday time off, FLMA, tuition reimbursement, and many others, This costs the company a lot of money and so usually your pay would go down, but your benefits should far exceed that loss of pay.
I worked this way before. I was an independent contractor and got paid more per hour but I did not get any benefits. Now my overall salary is lower, but my benefits are so much better.
And like what others say if this is not the case, or you feel you can do better elsewhere there appears to be many jobs what is stopping you?