Buddhist "code of ethics" on talking about other religions I took a friend interested in Buddhism to a centre. This person is Catholic and doesn't want to change that; she is very satisfied with her religion. However she was curious about Buddhism and specially meditation.

At the end she was a bit disappointed because there were 2 mentions of other religions (catholics and other buddhist schools) that she thought were driven by a big "pride", for example: "Here we don't do this...in other centres they do"; "We value this, catholics don't".

I didn't have the same interpretation, however I agree one should be very careful on talking to an open public about other religions and traditions, as it can be very easily misunderstood. We don't need to use other religions to make a point.

So, the question is: Is there any Buddhist code of ethics on that? In the Vinaya maybe?
What you've described is probably very common in meditation centres, unfortunately.

This isn't from the Vinaya proper, but in the Brahmajāla Sutta, the Buddha goes over many views, starting with superficial views his followers have of him. Here's an excerpt from Bhikkhu Bodhi's translation:


  
  "It is, bhikkhus, only to trifling and insignificant matters, to the minor details of mere moral virtue, that a worldling would refer when speaking in praise of the Tathāgata. And what are those trifling and insignificant matters, those minor details of mere moral virtue, to which he would refer?
  "'Having abandoned the destruction of life, [omitted for brevity]' It is in this way, bhikkhus, that the worldling would speak when speaking in praise of the Tathāgata.
  
  "Or he might say: 'Having abandoned taking what is not given, [omitted]'
  
  "Or he might say: 'Having abandoned unchaste living, [omitted]'
  "Or he might say: 'Having abandoned false speech, the recluse Gotama abstains from falsehood. He speaks only the truth, he lives devoted to truth; trustworthy and reliable, he does not deceive anyone in the world.'
  
  "Or he might say: 'Having abandoned slander, the recluse Gotama abstains from slander. He does not repeat elsewhere what he has heard here in order to divide others from the people here, nor does he repeat here what he has heard elsewhere in order to divide these from the people there. Thus he is a reconciler of those who are divided and a promoter of friendships. Rejoicing, delighting, and exulting in concord, he speaks only words that are conducive to concord.'
  
  "Or he might say: 'Having abandoned harsh speech, the recluse Gotama abstains from harsh speech. He speaks only such words as are gentle, pleasing to the ear, endearing, going to the heart, urbane, amiable, and agreeable to many people.'
  


Also, in the Theragatha (found in the ) we have the verses by Vangisa Bhikkhu (according to ATI, the bhikkhu whom the Buddha designated as his foremost disciple in the composition of spontaneous verse):


  
  One should speak only that word by which one would not torment oneself nor harm others. That word is indeed well spoken.
  One should speak only pleasant words, words which are acceptable (to others). What one speaks without bringing evils to others is pleasant.
  Truth is indeed the undying word; this is an ancient verity. Upon truth, the good say, the goal and the teaching are founded.[19]
  The sure word the Awakened One speaks for the attainment of nibbana, for making an end of suffering, is truly the best of words.