I wonder if the map is different, or if they changed the firmware of the device to display things differently. I am not aware of any place where you can download old versions of the City Navigator map. There was another similar thread here awhile ago, where somebody liked the rivers better on the old map.
You can download/install old versions of the device firmware however. Not sure if that would make any difference.
http://www.gawisp.com/perry/drive/The appearance of Garmin maps can be customized in a couple different ways however. One of them is the map theme. You will find theme files in the ~\Garmin\Themes\Map directory on the device. They are just .xml files that you can modify in any text editor. For starters, have you tried the different built-in themes? They might help with what you want. You can choose them with the Theme menu on the device. You can make a copy of one of them and then edit to create a custom version.
There is also a little program for this. I don't know if railroads can be customized with a theme however, I have only used them for roads. This program will give you a more user-friendly way to edit themes. I have not used it myself, but the author's other software is excellent.
https://www.pinns.co.uk/osm/theme_maker.htmlThe other way to change the map appearance is by using custom types. This is an older system and also much more powerful than the themes feature. You should be able to make the map look like whatever you want this way. The same author has a very nice program for this
https://www.pinns.co.uk/osm/typwiz5.htmlI (and others here) use this free program to create and edit custom types (.typ files). It works very well, but assumes that you already have a full understanding of making Garmin maps, so probably not a good option for a regular consumer
https://sites.google.com/site/sherco40/So, there are several options to accomplish what you want without changing the map itself. The thing is, Garmin typically does not use a .typ file with City Navigator, so you need to create a new one to use this feature. And you cannot change the zoom levels at which a feature is displayed by using a .typ file.
That is what makes me wonder if the change you are seeing is the result of new device firmwar? I have a DriveSmart 61 myself, still running the original map and firmware. It shows railroads as very conspicuous striped lines until I zoom out to 1.2 miles, where they disappear. Is this what you prefer (personally, I really dislike this, it just clutters the map and I'm not interested in railroads).
I am running firmware version 3.40. There have been quite a few firmware updates since then! If it were me, I would think back to the point when you most recently updated your map and firmware, then try to find the previous firmware version from the link I posted. For example, the most recent firmware update was 12/20/2018. Is that when the problem began?
To revert to old firmware, you need to access the hidden .System folder on the device. If using a Windows computer, you will need to change it to Mass Storage mode (not necessary on a Mac)
Go to the Volume screen
Press the upper right hand corner of screen for 10 seconds.
The Developers Screen should appear
Scroll down to MTP SETTINGS
Change to MASS STORAGE
Now do this on your computer

Copy the file named GUPDATE.GCD to your computer as a backup. Ths is the installer for the firmware (not the firmware itself). Now take the firmware file that you downloaded and change the name to GUPDATE.GCD and place it in the hidden .System folder, replacing the old file. Restart the devcie and it should ask if you want to install old firmware.
It is always a good idea to have a full backup of your device before changing anything. To do a backup, just copy everything to a folder on your computer (INCLUDING the contents of the hidden .System folder).
Also.... if you aren't comfortable with messing around with this kind of thing, DON'T DO IT.
