Any
generic satellite receiver gets all of these free channels:
http://en.wikipedia.org/wiki/List_of_free-to-air_channels_at_28%C2%B0E
A Sky box, without a valid subscription, acts as a generic satellite receiver.
A Freesat box actually receives fewer channels, since it's pre-configured to receive just a subset of those listed in my link. (However you can add further channels from the list manually if you want). It might also add in a few 'red button' facilities (and/or recording facilities) but, at it's most basic, a Freesat receiver won't give you anything that an old Sky box can.
It's worth remembering that, although there are more free channels available with a satellite dish than with a terrestrial aerial (i.e. via Freeview), they might not include the ones you want. For example UKTV doesn't transmit its channels (such as Dave, Yesterday, Drama and Really) as 'free to air' on satellite. If you want to receive those channels you'll need either a Sky subscription or a Freeview aerial.