whats the difference in the actions between Remington's Model 7 and Model 700

I am not sure of all the differences but the M7 and M700 are very similar. The most obvious difference is the size. The seven is shorter and as I recall does not come in a long action. It is chambered in short cartridges like 243, 308 and WSMs. And, does not come in a left hand version..

Action is shorter,lighter and there is a small trigger difference although a 700 can fit but with some fitting as well as scope mounting hole spacing.

Model 7 is a shorter rifle.. 20" barrell I belive.. And is a really nice setup.. I love mine in 243..

As mentioned above, the M7 is made only for the short cartridges, and as sporting rifles only, not vartminters or target rifles. It is about the only thing Remington still makes that I would consider buying these days.....