Recently I've been covering topics that have to deal a bit on a deeper level when it comes to Android and iOS, and that's the common practice of either rooting or jailbreaking devices. Are you familiar with the terms "root" and "jailbreak" but not sure what they mean? Then I'll refer you to my posts here, here and here to give you an idea, which I would recommend reading before trying to read this post. Without any prior knowledge, all of this will probably end up sounding like gibberish.
In this article I'm going to cover another topic that's related to rooting on the Android side, which is getting down to some specifics on the differences between the terms "custom ROM" and "mod". It's a confusing subject because they're two different things, but they're also technically the same.
When people hear the term "root" they're likely to hear the phrase "custom ROM" in the very same conversation. Why? Because custom ROMs are awesome, and for a lot of people it's the whole reason they even bother rooting in the first place. Custom ROMs are what some developers spend a lot of time putting together in order to make what they consider to be improvements to the phone. Custom ROMs are different from the stock UI that the manufacturer provides for you, and depending on the ROM they can be different in many ways. Some ROM developers like to change a lot of things: the software version, the speed of the phone, the skin of the device, the way the icons look, the font, etc. Custom ROMs are a great way for somebody who is new to rooting their Android to visually grasp the concept of everything you can change. It's a premade layout that differs from the same UI that you've been dealing with since the day you got the device and often times enhances the performance of your phone.
So we know what custom ROMs are, but now what about mods? You may have been under the impression that mods were custom ROMs, and technically you would be right (which is the best kind of right, yes?) The terms can be seen as interchangeable, but you can also mod specific parts of the device without ever installing a custom ROM. A mod can be anything you change about the phone. You see, once you first root the device nothing about your phone has changed other than you have root access, and you probably have SuperSU installed on your device all of the sudden. Your phone is not magically amazing just by getting root access - you have to customize it yourself to make it that way. You're still using the stock ROM and stock everything else. At this point, you can either choose to install a custom ROM (a whole bunch of mods melted together in one .zip file) made by somebody else, or you can mod your own phone by picking and choosing the perfect mods for you one by one. I've always seen a mod as being a singular change; a custom ROM generally consists of a cluster of mods, but since it all comes in the form of one file it could also be considered one big super mod.
Like everything, there are pros and cons to choosing a custom ROM or picking and choosing your mods. For beginners I would recommend going with the custom ROM, mostly because you're already going to know what works and what doesn't work with the modifications that the developer used. Some custom ROMs, especially in earlier stages or with newer devices, don't have everything working. You'll see a ROM here and there where SMS, data, Wi-Fi, etc. isn't working yet. The important thing is that they're able to let you know beforehand on their info pages, and as long as you follow directions exactly as written you shouldn't have any surprises after flashing a custom ROM.
For more experienced users, individual mods might be the better option. When you first discover custom ROMs, that burning internal desire to have your phone do something - anything - differently is satisfied for a little while. A little while. Then you get to the point where you get nit-picky about things. You don't like this, or this or this about the ROM. You think this could have been done differently or you would rather have x function back from the stock ROM, which this ROM didn't include. Even if you move on to another ROM, the same thing happens. You'll probably be happy for a little while, but in the end it's still something that somebody else created according to their own personal taste. By learning how to impletement your own choice of mods from singular sources, you may be able to remedy some of the issues that you're having with premade custom ROMs without having to switch ROM after ROM looking for the perfect custom ROM (unless you're just a serial ROM switcher, like me). Alternatively, you could also use smaller mods on a stock ROM just to tweak certain things. Maybe you really like TouchWiz or Sense and you just wanted to change the way the notification bar looks, or the font on your device. Little mod packages can take care of that easily.
Obligatory TL;DR: Custom ROMs are compilations of mods to make one big super mod, and individual mods are available for the fine tuning.
As always, before flashing any changes over to your rooted Android it's always recommended that you make a NANDROID backup, just in case something goes wrong. I also recommend reading whatever guide the developer has provided you with thoroughly to avoid any unnecessary complications.
Readers, what are some of your favorite smaller mods and tweaks that you have made to your Android device? Share them with us in the comments below!