On a smart phone, if you know how to, you can have more than one app running at the one time and swap between apps and copy and paste information between apps. This is really great feature if you know how to use it and it can allow you to do things otherwise you couldn't do.
However what you can't usually do on a phone is run the same app more than one time. Like you can't run email more than once which means if you want to compose two messages at the same time and have information in relation to each copied from one to the other, you can't do it.
Or if you have two photos that you want to compare one to the other, you can't have two versions of your photo gallery app running at the one time and compare photos. I wanted to do this recently where I had a photo that was taken 45 years ago and wanted to compare it with a photo I took more recently on a trip to the same place.
But I've work out a way to overcome this problem. There are many apps, on the app store, that virtually do the same thing. Like there are multiple photo gallery viewers or just photo viewing apps. So you just install a second one of what you want to do. Admittedly it may not work exactly the same as the first one but the difference would not be much. That way you can run both apps at the same time, and in the case of the photos compare the photos
On some smartphones and later Android versions you can actually split the screen into 2 and have the 2 apps on the screen at the one time, both of which you can see.
In the case of most email you don't even have to install a second email app. You can use the app version of email as well as a browser version. I had this situation recently. I had previous sent emails that had been sent to about 50 people. I wanted to copy the email addresses and send a new email to those same 50 people. Actually the email app that I was using, Gmail, would not allow me to copy and paste the 50 email addresses. It would only repeat the last email address 50 times. But by going into the web browser and calling up the Gmail website, I was able copy the 50 email address from the Gmail app and post it into the Gmail web page.
Actually sometimes you don't even need to use two versions of the same thing. Like on web browsers. Most phone web browsers allow you to have multiple tabs open at the one time. And you can swap from one TAB to the other. I have had situations where I would open the same web page multiple times in different tabs on the web browser and be reading different parts of that webpage in each tab. This can be handy if you're reading a web page that refers to something else that was previously written on the same page. Rather than having to lose your place where you are on the web page, you can open a new tab find which you have previously read, read it and then swap back to the other tab and continuing at the exact place where you left off.
All the above is thinking outside the box. With technology there are often limitations as to what you are allowed to do, but if you think a bit differently you can get around those limitations.
If you want to learn how to do any of the above, contact me.