While Salyut 6 orbited for an extended period of time, Voskhod 1 was only in space for about a day.
However, since it was at a higher inclination, it had a better chance of having line-of-sight access to atmospheric phenomena in the general area of the North Magnetic Pole, which was in a very different location in 1964 than it is today!
Question: Both missions were launched from roughly 46° degrees north latitude, but they were very different in nature, so there's no reason to expect the declinations to be the same, of course. Here I'm simply asking why Voskhod 1 was at an inclination of 64.7° degrees while Salyut 6 at 51.7°. What were the factors determined that those different inclinations were optimal for those missions?