Current cx bikes and gravel bikes have pretty similar geo. A cannondale super x and topstone are essentially identical for example, and in fact the super x has longer chainstays and a barely slacker hta and lower bb. Some vary more, specialized's diverge is a bit longer and has a lower bb than the crux. Even the pure "cx race" bikes have slackened the hta and gotten a little lower since like 10 years ago.
What is probably a more significant difference is that gravel bikes generally have more mounting provisions for racks and bags and whatever, BB height meant for a 40ish mm tire instead of a 33, maybe more clearance but cx frames are fairly generous despite being meant for smaller tires due to mud concerns. Plus only uci rules require 33s so most racers can, and do go with larger tires.