What is the difference between Wi-Fi and Cellular connections?

Confused about the difference between cellular data and Wi-Fi? There many technical ways to explain the difference between the two, but we’re going to try to simplify this as much as possible by highlighting the main points.

This table shows the major differences between Cellular Data and Wi-Fi:

Cellular Data Wi-Fi
Offered by mobile carriers (AT&T, Verizon, Sprint, T-Mobile, etc.) Set up yourself in-home, by IT at work, or offered by Internet Service Providers (ISPs) 
Covers large areas (cities, towns, etc.) Location-based covers small areas such as cafes, your home, or airports
Users purchase plans for a certain amount of data per period (10 GB, 50 GB, Unlimited, etc.) Typically, Wi-Fi has no limit for the amount of data
Useful for simple internet activities (checking Email or Facebook) Generally much faster than cellular, perfect for data-intensive activities (Skype, Netflix, YouTube, downloading music, etc.)

(Source: Boingo)

Radio Frequencies: Since Wi-Fi is a local area network (LAN), it can only provide internet access within a short-range. Devices can exchange data on the internet using 2.4 GHz UHF and 5 GHz radio waves. This means that bandwidth is very high, which allows users to do pretty much anything they want on their devices, from checking emails to streaming videos.

As stated in the above table, Cellular can cover a wide range, even entire countries at this point. When you’re searching on your web browser or checking Facebook, you are consuming data. It can potentially be just as fast as Wi-Fi, but can be way more expensive. Cell phone frequencies vary depending on the provider, but many phones have both 3G and 4G LTE. 3G frequencies are usually between 800 and 1900 MHz, and can handle talk, text, and basic internet functions. 4G LTE frequencies are a little different than 3G. 4G LTE started in the late 2000s and is compatible with 3G, which means that it can handle talk, text, and data-heavy activities. Its frequencies are classified by Bands, which are groupings of radio frequencies used by mobile networks. Many mobile networks support up to 4 bands, ranging from 700 MHz (Band 12) to 2100 MHz (Band 4).

Switching from Wi-Fi to Mobile Network

Smartphones support both Wi-Fi and cellular connections, but (without Speedify) they do a terrible job of switching between the two. 

Sometimes apps or webpages won’t even load unless you turn off Wi-Fi to switch to cellular, even though there are settings that allow you to switch from one to another. Speedify fixes all of these problems, letting you move from Wi-Fi to Cellular and back to Wi-Fi without over dropping a Skype call, going offline, or having your music stop. 

"Speedify did smooth out a bump in my home wireless network, which uses a pair of linked AirPort Extreme routers for wider coverage. There’s a known dead zone in my hallway right between the two routers, but Speedify successfully filled this brief gap using cellular connectivity, allowing downloads or streaming video to continue without missing a beat," Macworld

iOS phones have something called Wi-Fi Assist, where phones will switch from a poor or weak Wi-Fi signal to the user’s cellular data. The issue with this is that the phone will stay connected to the internet over cellular, which may cause users to use up a lot of data. Apple does note on its site that it engages for foreground apps, not background tasks. But in many cases, users can use hundreds of megabytes or gigabytes without even realizing it. This is an automatic setting for iOS 9, which many people have decided to opt-out of. If you have an apple phone, HERE is how you can disable those settings.