See regular MSc is a 2 years course and PhD usually takes 5 years to complete so if you do MSc then PhD then you will have to spent 7 years where as if you go for Integrate phD program then you will be able to get both the degrees in 5-6 years. So you save time. Now for Integrated phD you can't leave the course just after MSc so you have to complete the whole course itself in order to get the degree.

Some of the top institutes for Integrated PhD in physics are:

• TIFR
• ICTS
• IISc
• IUCAA
• IISER's
• NISER's

Also in order to have a more open option you can go for Joint MSc PhD courses in IIT's through IIT JAM in which you can leave after your MSc or join PhD.

To know more about Physics as career visit the link below:

https://www.careers360.com/courses/physics-course

I hope this answer helps. All the very best for your future endeavors!