Except size and capacity, you may notice the 3 letter codes on most Li batteries like ICR, IMR, INR, NCR, etc. printed on the battery like the Samsung ICR18650-26F, INR18650-30Q, Panasonic NCR18650B, etc. These are various types of Li-ion batteries . The 3 letter codes are manufacturer codes, and most but not all, use this as a standard way to refer to the different types of cells.
The first Letter "I" just means that the cell is a Li-ion rechargeable.
Second letter refers to the cathode material.
The last letter "R" just means the cell is round.
ICR = Li-ion Rechargeable, the "C" = Cobalt.
Lithium cobalt oxide or ICR Batteries are well known for having high specific energy, even amongst its powerful li-ion brothers. Therefore when using an ICR, a PCB protection circuit should always be used in the final product.
IMR = the "M" stands for Manganese, or "Mn".
Lithium manganese or IMR Batteries are a classic standard of Li-ion cells, featuring high drain and steady performance.
INR = the “N” stands for Nickel.
Lithium manganese nickel or INR Batteries are a hybrid chemistry that adds nickel to increase capacity. While relatively safe on its own, it is still recommended to add a PCB when adding this to any electronic device.
IFR = the "F" stands for the element "Fe".
What about Panasonic NCR18650B?
The name NCR18650B is just Panasonic’s part number and it’s also a Lithium Cobalt battery, like an ICR cell. Panasonic does put some additional safety features that make it safer than any ICR cell.
The NCR18650B is available with and without protection. Again for protected cell, it may be offered as a rewrapped under different brand or same brand but the dimension will be longer and wider, so it may not suit some devices.