How would you describe the key differences between the product manager role and product marketer role?

PMM and PM roles vary greatly across companies, but there are some common differences:

1. PMMs are the market and competitor experts. Unless the company is very small, a PM who is an individual contributor typically "owns" a narrower segment of the overall product. In contrast, a PMM typically looks across a wider range of the product and market. So, the PMM should bring that knowledge and experience to bear in the relationship 
2. PMs are the product experts. Unsurprinsgly, PMs know more about their product area than anyone else. So, if there are questions or decisions that need to be made on the product roadmap, customer feedback, user experience, etc, the PM should own those.
3. PMMs are the conduit with the rest of the go-to-market org. A Product fails if no-one hears about it or uses it. A PMMs most important role is to help evangelise the product to internal stakeholders as well as customers. PMMs play a crucial in connecting the dots between cross-functional stakeholders to drive programs forward.
4. PMs are the customer experts. Partnering with design, PMs should have the best lens on customer experience. PMs should be defining the overall end-to-end user experience.

The product manager (PM) decides “what” to build and “when”, and is accountable for delivering the product or feature that delights customers. The product marketer (PMM) informs “what” to build, and is accountable for driving the demand for what has been built.

Both require deep customer and market insights. Both need to think strategically about how to differentiate your product in your space. The difference lies in execution.

On a day-to-day basis, the PM works very closely with designers and engineers to discover, design, scope, and implement what needs to be built. You are much more focused on your product’s functionalities as well as its UI/ UX.

The PMM, on the other hand, works very closely with go-to-market teams. You are focused on positioning the product, translating features into compelling customer messages, and enabling your marketing and sales colleagues.

Metric wise, I tend to think the PMM is more responsible for acquisition, i.e., getting customers into the product; and the PM is more responsible for retention, i.e., getting customers to stay with the product.

Think of a restaurant with front and back of the house. Back of house is prepping, cooking and organizing the food for front of the house to position, serve and engage the customers. Another way to look at this is front of the house understands what the customers want, thier expecations, reactions and provides feedback to back of the house to prioritze what food is being prepared. This symboitic relationship is anlogous to PMM (front of house), PM (liason between front and back of house) and engineer (back of house). PMM needs to understand the customer persona, market and positioning. PM should understand how the personas, market and positioning impacts the product strategy while prioritizing what engineering works on and verifies if product is meeting requirements.