Both are the different courses & Choosing a course totally depends on your interest. Nothing is tough to study it only depends on your interest.

If you are interested in Ayurvedic medicine you should choose BAMS and if you interested in dentistry you can go for BDS.
After completing the programme BAMS, Many organizations are working in the manufacturing and research field in abroad are requiring the professional in this field. The candidate having the BAMS (Bachelor of Ayurvedic Medicine andSurgery) degree is eligible to be called as a doctor and eligible to do the private practice. BDS is the educational programme for the Dental Surgery in India.

In this course, the students learn & taught about the denture, dental problems and surgery. After completing this course you will be hired by Dental colleges, Hospitals etc.

Now you can comare both the fields as per your interest.

Good Luck!