This[1] is a paper that shows what each operating system tracks and what security model they use. Android generally tracks more and has less effective sandboxing.

[1] https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&d...

The paper you linked is absolutely trash. The actual "meat" of the article is only two pages, and contains nothing of substance, presumably because the authors themselves admit it's "secondary research where we have collected the data from IEEE Xplore and Wikipedia". It also contains some hilariously bad takes like that Android "is not fully stable because as android is free ware". As for the claim that it has less effective sandboxing, that's just a claim taken at face value from an article from 2014 and is no way indicative of how secure iOS or Android is today.

I wonder why you are being downvoted. The abstract of that paper alone doesn't make me confident that the authors know what they are talking about:

Abstract - Mobile operating system is a light weight operating which is used in mobile device. Some operating systems have additional features like sensor embedding and also OTG. In this paper we are going to compare between android and iPhone Operating System (iOS) mobile operating systems that available in the market which is more specific various issues. The issues which we are going to discuss in this paper is not only concern to mobile customers but also concern to software developers. The security requirements for MOS are Memory Randomization, Encryption, Data Storage Format and Built-in Antivirus. Memory randomization ensures that the memory regions of mobile application as well as system shared libraries are all randomized at device and application start-up. In this paper we want compare and analyse the operating system of the Android and iOS.