The MacBook Pro "Core i9" 2.9 15-Inch (2019 True Tone Display, Touch Bar, Four Thunderbolt 3 Ports) technically is a "configure-to-order" configuration of either the MacBook Pro "Core i7" 2.2 15" Touch Bar/Mid-2018 or MacBook Pro "Core i7" 2.6 15" Touch Bar/Mid-2018, but also is documented as a separate model for reader convenience. Other than processor, these models can be configured identically.
The MacBook Pro "Core i9" 2.9 15-Inch (2019 True Tone Display, Touch Bar, Four Thunderbolt 3 Ports) is powered by a 14 nm, 8th Generation "Coffee Lake" 2.9 GHz Intel "Core i9" processor (8950HK), with six independent processor "cores" on a single silicon chip, a 12 MB shared level 3 cache, 16 GB of onboard 2400 MHz LPDDR4 SDRAM -- which could be upgraded to 32 GB at the time of purchase, but cannot be upgraded later -- either 256 GB, 512 GB, or 1TB of onboard flash storage standard, and dual graphics processors -- either an AMD Radeon Pro 555X or 560X with 4 GB of dedicated GDDR5 memory -- as well as an integrated Intel UHD Graphics 630 graphics processor that shares memory with the system.