What does a developer product marketing manager need to be exceptional at compared to product marketing manager?

If you are targeting developer mindshare and attention, be ready to discuss your product in a detail-oriented, transparency-driven way and explain the business value for their situation. So naturally, for being successful in developer product marketing one has to put the product first when talking to developers, not marketing.

Typical product marketing managers are great with up-leveling the conversation which might not always work in their favor with developers. Developers generally are well aware of equivalent/substitute products that exist in the marketplace, so developer product marketing managers require an additional inquisitiveness to go beyond their domain and hit refresh fast to be relevant with their developer conversations. Focus on building your PMM skills and then supplement them with good product knowledge (maybe even hands-on) would be really helpful in building a developer product marketing career.

This is also why I think a great Dev PMM doesn't really need any PMM experience. Look to solutions architects, pre-sales engineers, or just developers in your space. It's much easier to learn PMM frameworks than it is to learn a new domain, and gain the respect you need to tap into the best insights

I’d sum it up with the ability to tell a complicated story quickly and concisely as well as the ability to nuance your work between developer personas and decision maker personas, and understand how partners and end users fit into the equation. I find that sometimes as a developer marketer, I’m doing the same things as my Core PMM peers and at other times I’m working on a completely different set of deliverables with a different tone. 

So to excel at developer marketing you’d need to be able to go broad compared to when Core PMM needs to go deep. For example, I don't write as many blogs or build as many decks as I used to when I wasn't focused on developers, but I still need to do that set of work every now and then. But in addition to that, I’ll work with partners, work on hackathons, tap into developer specific channels, etc. 

The key thing is will he or she be able to effectively fight for developers to have a distinct voice within your organization, especially for what they need to do in order to be successful. 

I've been at many companies where developer marketing or the B2D platform play was secondary or complementary to our key enterprise B2B play. T

There's some baggage that comes with that from a GTM standpoint... notably a visual and verbal identity that doesn't fit all sizes. 

There's a myth that developers don't like marketing. I disagree. Developers don't like bad marketing (who does?) and the number one cause for that is if you speak to developers the same way you would to your ITDM/buyer personals. It never works and makes you look like "shirts". 

The best B2D product marketers will therefore help stand up a different (but complementary) look and feel for their developer audience. One that can co-exist with the core company brand and sometimes even hijack it (e.g Salesforce). 

There aren't developer PMMs and non developer PMMs on my team. A PMM is a PMM and they need to be exceptional at 1) knowing their audience 2) Knowing their market and competition 3) Knowing that content is only as good as the distribtuion plan you put behind it. The third bullet there is the difference - know what channels developers hang out in. Don't make your product times square with ads. Make newsletters. Write long form tutorial and reference architecture content. Create technical demos. Don't use cutesy animations and inspirational campaigns for developers, etc.