Married seperate or married jointly?

whats the difference between filing married jointly and married seperate? I made around 45k this year with 1 full time job and 2 at home business... i will need to file long form due to my deductions.... my husband was laid off atleast 4 months total... and made a little less than i did.... we have 1 child together and 1 child he can only claim (my stepdaughter) What would be the difference between filing jointly or seperate? would seperate be more beneficial