First, let me post the description for Wall of Ice as a reference:
Now, the description for Wall of Force:Saving Throw: See text
Hemisphere: The wall takes the form of a hemisphere whose maximum radius is 3 feet +1 foot per caster level. Thus, a 7th-level caster can create a hemisphere 10 feet in radius. It is as hard to break through as the ice plane form, but it does not deal damage to those who go through a breach.
The character can create the hemisphere so that it traps one or more creatures, though these creatures can avoid being trapped by the hemisphere by making successful Reflex saves.
Ok, now my question. Does a Wall of Force allow a caster to trap someone without a save? It does not mention trapping someone, but it does mention the spherical shape. (If you can't trap someone, what's the sphere shape for?) Also, WOI mentions a save, but WOF clearly says No Save in the summary.Saving Throw: None
The caster can form the wall into a flat, vertical plane whose area is up to one 10-foot square per level, or into a sphere or hemisphere with a radius of up to 1 foot per level.