RISE and RVI are complementary. RVI’s interest in SW and RISE’s interest in SW are different. RVI’s has a stake insofar that the specs are produced and adopted, while RISE’s stake is efficient execution towards productization/commercialization.
RVI works on specifications (ISA, IP blocks, SW interfaces e.g. BRS, psABI, etc). Such work involves feedback from subject matter experts in relevant communities (compilers, kernels/hypervisors, etc). Some of this feedback may involve the creation and analysis of proofs-of-concept and prototypes. Usually, such contributions from RVI members are at-will, informal or or limited to engineers pushing specific spec changes. RVI does play a role in overseeing, staffing or funding such work, and production-grade code as part of upstream projects is not itself a goal - just enough work to meet ratification requirements. Proof of concepts still need further work to get upstreamed, and may have dependencies across a wide set of projects... such work becomes the responsibility of individual members.
RISE's focus is commercial readiness. RISE is a more efficient way of executing on any RISC-V SW enablement project than any one individual member, because of the ability to staff, fund and prioritize/uncover/resolve dependencies as necessary. RISE is able to work across multiple projects and organizations and is able to plan better by seeing more context "over the horizon", as RISE members are upfront about their roadmaps as far as the affected projects go.