inorganic chemistry - Energy of electrons in the same subshell

So I have this quote from wikia (it's similar to my lecture pdf file) but I don't fully understand the statement

Although it is commonly stated that all the electrons in a shell have the same energy, this is an approximation. However, the electrons in one subshell do have exactly the same level of energy,[6] with later subshells having more energy per electron than earlier ones. This effect is great enough that the energy ranges associated with shells can overlap

In this statement, does it mean for example:

1) "Each" electron in the subshell 1s and "each" electron in subshell 2s have the same amount of kinetic energy.

Or

2) It means :"All electrons 1s have the amount of Kinetic Energy & All electrons 2s have the same amount of Kinetic Energy. However each electron in 1s doesn't have the same amount of Kinetic Energy compared to one electron in 2s" ?