What are the major differences between the two? I find that the Holosights are, sometimes, more expensive. Are the two used differently? Any ideas are appreciated.

Holosight is more for close range shooting, faster on target. Scopes are better for longer range, accurate shooting. Good scopes cost a lot more than a Holosight.

Quoted: What are the major differences between the two? I find that the Holosights are, sometimes, more expensive. Are the two used differently? Any ideas are appreciated.

Scope = magnified view for longer range precision shooting.  you don't need a scope to shoot long range, but it makes it easier.  4 x 32 means what you are looking at will appear to be 4 times closer, the 32 is the size of the scopes diameter, the larger the number the more light it will gather, and the clearer an image will be at its maximum range.  4-9 x 50  the 4-9 means you can adjust the zoom factor from 4 to 9 times closer.

Red dot = a optical sighting system were a small red dot is projected on to a clear glass ring or pane.  when properly aligned (zeroed) this dot is then used as a reference to where the bullet will impact. most red dot sights are non-magnified, but there are some that are.  you can also buy add-on units that will magnify the dot as a scope would. A red dot sight needs to be viewed from a limited angle in order to be on target. Red dot use very little energy and can go several years on one set of batteries.

Holosite = A holographic display of a reticule is projected onto a pane of glass. the advantage over a red dot is no matter how you look through the optic, the reticule will always be on the point of impact if the weapon and sight were zeroed properly. The holosight uses a lot more energy then a red dot, which requires more batteries over the life of the sight.

Laser sight = A visible laser is aligned with the bore of the weapon to give the shooter a general idea where the bullet will impact. only useful for close range since even very expensive lasers will "bloom" after 75 yards, meaning the "dot" will be larger then the point of impact.