sixty minutes of easy running at ave 70% max HR, or sixty minutes with the same ave HR on a spin bike. Aerobically, do I get the same benefit from each?
In short, there is a measurable amount of "carry over" in cross training that will be of benefit. But SPECIFICITY is ultimately what's crucial when training for a specific goal, whether it's running a blazing 5,000, or swinging a golf club or doing a bunch of pull-ups (so you can impress others stuck in the gym with you).
Your cardiovascular system will incur the same benefits/risks at a given HR, but your muscles and brain/nervous system will not, and these are the physiologic components propelling you during a given task. But remember: you're not just training a specific "system"...you're training YOU.