Difference between neutral Karma and no Karma I've read an article that mentioned something like neutral Karma, and it seems it is no more/less than no Karma. Does anything differentiate neutral Karma from no Karma?
To the best of my knowledge, there is no such thing as neutral karma. As you rightly surmise, it would be the same as non-karma. This is because karma in Buddhism refers to ethical intention, not the act itself:


  cetanāhaṃ, bhikkhave, kammaṃ vadāmi. cetayitvā kammaṃ karoti — kāyena vācāya manasā.
  
  It is intention, bhikkhus, that I say is karma. Having intended, one performs karma, by body, speech, or mind.
  
  (AN 6.63)


In Theravada Buddhism, consciousness without ethical intention is called "avyakata" or "indeterminate", and is "karmically neutral", which is not the same as being "neutral karma", a term that doesn't make much sense from a Buddhist point of view.


  avyākata
  
  lit. 'indeterminate' - i.e. neither determined as karmically 'wholesome' nor as 'unwholesome' - are the karmically neutral, i.e. amoral, states of consciousness and mental factors.
  
  They are either mere karma-results (vipāka, q.v.), as e.g. all the sense perceptions and the mental factors associated therewith, or they are karmically independent functions (kiriya-citta, q.v.), i.e. neither karmic nor karma-resultant.
  
  http://www.palikanon.com/english/wtb/a/avyaakata.htm