What is the difference between a normal SIM, Nano SIM and Micro SIM card?
There are different sizes for SIM cards. The very old SIM cards had a quite large format, were replaced by Micro SIM cards, which are a bit smaller and recently there are also Nano SIM cards. Special Apple relies on Nano SIM cards.
There are also adapters for the individual cards, but we always recommend to use the size that is needed in the phone. Usually you can order a Micro or Nano SIM card for free from your provider.