From what I know of Apollo (which is a lot less than Relay, having worked on the RelayModern compiler), this comparison is pretty good.
(1) is true, for the most part, from the developer point of view. But when you're using the compatibility mode of RelayModern (i.e. sending out a legacy query that contains modern fragments), Relay does runtime query building from the Modern fragments.
(2) Relay allows you to define updaters for mutations, which lets you write client-defined data transformations. This may not be as complex as what's happening in the Apollo client, but I don't have the experience to say. See http://facebook.github.io/relay/docs/mutations.html#updating...
Edit: I'm Matt, and I work on a sibling team to Relay at Facebook, and helped build RelayModern's compiler.
(1) is true, for the most part, from the developer point of view. But when you're using the compatibility mode of RelayModern (i.e. sending out a legacy query that contains modern fragments), Relay does runtime query building from the Modern fragments.
(2) Relay allows you to define updaters for mutations, which lets you write client-defined data transformations. This may not be as complex as what's happening in the Apollo client, but I don't have the experience to say. See http://facebook.github.io/relay/docs/mutations.html#updating...
Edit: I'm Matt, and I work on a sibling team to Relay at Facebook, and helped build RelayModern's compiler.