Is there any difference in how minimum distributions are calculated between an IRA and a profi sharing plan? I just talking about the amount of the required diistribution.

Not if the participant/IRA owner is alive. If you are calculating a participant's MRD in a profit sharing plan or the IRA owner's MRD, you would use the Uniform Lifetime Table unless the individual is married. If the individual is married and the spouse is the only designated beneficiary for the entire distribution calendar year and the spouse is more than 10 years younger than the individual, you then will use the Joint and Last Survivor Table.

Also, IRA's can be aggregated and the w/drl for one can be taken from another. But PS plans generally cannot be aggregated and a w/drl must generally be taken from each one.