Also question is, is pay as you go cheaper than pay monthly?
Cheaper monthly costSIM-only plans allow you to keep your current phone. You can still get the benefit of a bundle of calls, texts and minutes for a single monthly rate. But the price is significantly cheaper than a phone contract, because it doesn't include the cost of a new phone.
Subsequently, question is, what is pay as you go plan? With Pay As You Go plans, consumers can choose between smartphones and basic cell phones or non-smartphones with Qwerty Keyboards or touchscreens and/or slider phones. Android smartphones by Samsung, ZTE or Huawei are available. You can purchase them directly from various no contract/prepaid phone companies.
Also Know, should I get a contract phone or pay as you go?
Monthly contract. With a monthly contract you agree a set monthly price, which usually includes a fixed amount of call time, data and texts. It can often be very good value compared to a pay-as-you-go deal and you will get a new handset (although you're likely to pay more for a newer model).
What is the difference between SIM free and pay as you go?
Sim free is generally a phone that is unlocked and usable with any network sim. Sometimes these phones can be a little higher in price. A pay as you go phone is typically locked to a specific network, the price will be a little cheaper than a sim free phone.