Deployment and delivery model
Both are cloud platforms delivered, in most cases, through a partner-led implementation. The structural question is which ecosystem your organisation already lives in, because that determines how much integration work you inherit on day one and who is available to do it.
Organisation size and breadth versus depth
Both target mid-market and enterprise buyers, and both scale down awkwardly if deployed without restraint. Breadth extends across sales, service, marketing and, in some configurations, operations. Depth is available in each area, but you pay for it in configuration effort, so scope deliberately rather than enthusiastically.
Implementation effort and channel coverage
Expect months rather than weeks for a genuine programme, dominated by data migration, integration and process design. Communication channels such as telephony and messaging are usually delivered through partner applications or separate contracts. Check current features on the vendor's site, since enterprise packaging changes regularly.
Total cost of ownership over three years
Compare programmes, not subscriptions. A realistic three-year figure includes licences for every user type, partner fees for the initial build, integration work with finance and service systems, internal time from your own operations and IT teams, ongoing administration, and training for each intake of new staff. Both vendors will model licences for you. Neither will model your internal hours, and those hours are frequently the difference between two proposals that appear similar on paper. Ask your partner candidates to estimate them explicitly.