​While creating a website or an application, the developer needs to focus on two important components; the User Experience (UX) and the User Interface (UI). Both these terms are related to one another – the User Experience is based on effective use of the mobile app and how the user enjoys using the app, whereas, a User Interface is the look and feel of the app, its presentation and the overall interactivity of a product.
Hence, while creating a mobile app, the developers need to work together on the UX and UI, but both require different skill sets. Let’s understand this with the help of an example: 

Take a look at the Facebook home screen. Everything you see in the top and side search bars “News Feed”, “Status”, “Video”, “Upcoming Events”, etc. – is all a part of the UI. So, what the User Interface ideally is that it helps you navigate within the app or website, for example, if you click on Events, you will be navigated to a page where you will be able to see all the events listed in your profile. A good UI is the one that is easy to use and helps navigate the user with ease.
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On the other hand, User Experience is when the user clicks on the Events tab, but has to wait for the events to download for more than a minute. Imagine you try to search for a long lost friend, but you can’t search it or get presented with a multitude of options that do not match your friend’s name. With this kind of experience, it is the UX designer that needs to be blamed for the poor performance. 

What are the first few logical steps after your roll out your mobile application? Let’s take a look:

1. User downloads the application
2. User opens the application
3. User looks at the various features and operating tabs to use the app

Here, the third stage is the giveaway if you have created a successful mobile application. It determines if the user (who has downloaded the app) is going to be an avid user of your app or is simply going to uninstall it because he/she doesn’t understand it. This is largely based on the design of your UI or UX. Let’s understand the ‘why’ behind that reason.

User Interface (UI)
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User Interface (UI) basically refers to the look and feel of an app. The basic presentation of the buttons/tabs on the screen and its design falls under the UI. The mobile should be visually attractive and easy to use. For example, Instagram; the layout of the app is simple and the interface is easy to manage. The functionality is quite simple, and every time there is an upgrade a notification is sent to the user.