Microphones
The first takeaway is that there are different types of mics. Among them are condenser mics, which capture more subtle sounds, and dynamic mics, which captures louder sounds. You regularly use condenser mics since your smartphone has one. Condenser and dynamic mics can be used for recording podcasts and voiceover with them both having their advantages. Condensers pick up more detail and have a crisper sound. The drawback is that they pick up on more background noise, which can be a problem when someone does not have a quite space to work in. Dynamic mics pick up less detail, but they also pick up less background noise.
The second takeaway is that mics have a polar pattern. This means the area around the mic from which sound is picked up. Omnidirectional mics take in sound surrounding the entire radius of the mic. (Your smartphone's mic is omnidirectional.) While unidirectional mics (also called cardioid mics) are more focused and take in sound from only one direction. Bidirectional mics take in sound from two directions. Why does knowing this matter? At its most basic, you want to make sure you are aiming the mic in the right direction to get the best recording possible as having certain mics off-axis can significantly impact the recording quality.
It's also important to pay attention to polarity when selecting a mic. Do you want a mic that can pick up sound from a lot of different directions without having to change the angle (think press conference)? Choose omnidirectional. Do you want a mic that is highly focused in one direction and reduces background noise (think one person talkinging into a mic)? Choose unidirectional. Do you need to record sound in front of a behind the mic (think recording an interview where one person is on each side of the mic)? Choose bidirectional.
