I'm new to electronics and IOT. I have a small project for a plant monitoring and automation system using esp32 and it involves many sensors such as soil moisture sensor, dht22 etc.

One feature that i wanted to add is a soil ph monitoring system. I'm looking at different sensors online and i found this one https://s.lazada.com.ph/s.RME5P

It has 2 listings of a soil pH Sensor. One with a 0-5V output and a 4-20mA output. What is the difference of the 2 and what should i buy?

 

4-20mA is a way more rugged signal and can be transmitted without sensibility to noise over long distances.
You can also use a 4-20mA signal with DC voltage inputs, just put a resistor parallel to the signal at the DC voltage input to turn the stable 4-20mA signal into a DC voltage signal that can easily be measured. Put this resistor close to the point of the voltage input.