Either we aren't understanding each other or we just have two different trains of thought.
iOS is just more efficient at handling background task.
There are a total of 9 background modes. Things like audio apps, navigation apps, VOIP apps, etc etc...
Apps that meet those qualifications like a 3rd party voice over IP app, navigations app, and/or an app wanting to update its information based on variables (wifi, battery percentage, etc) by utilizing background app refresh can function in the background.
Apps that don't have one of the 9 exceptions are suspended (in RAM) as soon as possible, however they can request time to complete a task like a download.
Apps function is suspended specifically to conserve battery life. If its a non essential app then it shouldn't be running.
The app will remain suspended in RAM and opening right back up where you left off unless its purged by another app/function that needed the RAM when it was in its suspended state.
Android and iOS function fairly similarly in this regard. And while iOS isn't perfect Android tends to have more apps that won't play by the rules and continue to run and needlessly waste battery in the background.
Because of that the more RAM the device has the more apps it can keep suspended in the background. Software optimization plays a roll too though. Android isn't as efficient with memory management so they tend to need more RAM than iOS devices.
Here is a video demonstrating how the S8 with 4gb of RAM purges apps the iPhone 7 with 3gb of RAM keeps suspended (on the second lap). Yes, its an unrealistic use case but illustrates the point.