With Silence, you can't play a Purify to negate Poison.
With Silence, you can't make any changes to your field at all.
With this, your creatures can still attack.
You can still play permanents.
Sundials gain one more counter, even if you can't use its ability. <- big one I didn't think of until now.
And your shields still block damage, even though other effects don't work. [I mean, whether a shield is moving or not, it's still a shield, right?]