<<<CCC 1031 The Church gives the name Purgatory to this final purification of the elect, which is entirely different from the punishment of the damned.>>>
A booklet on Purgatory was posted on EWTN and it seems to say that there are similarities between the fire of Hell and the fire of Purgatory. Also, it was published with ecclesiastical permission:
"APPROVAL OF HIS EMINENCE THE CARDINAL PATRIARCH OF LISBON
Cardinal’s Palace, Lisbon March 4, 1936
We approve and recommend with all our heart the beautiful little book Read
Me or Rue It"
The booklet Read Me or Rue it says
"CHAPTER 1 : WHAT IS PURGATORY?
It is a prison of fire in which nearly all [saved] souls are plunged after
death and in which they suffer the intensest pain.
Here is what the great Doctors of the Church tell us of Purgatory:
So grievous is their suffering that one minute in this awful fire seems
like a century.
St. Thomas Aquinas, the Prince of Theologians, says that the fire of
Purgatory is equal in intensity to the fire of Hell, and that the slightest
contact with it is more dreadful than all the possible sufferings of this
Earth!"
http://www.ewtn.com/library/SPIRIT/READRUE.TXT