Goblins or Orcs?

[Fingolfin of the Noldor]

in a 1954 letter to Naomi Mitchison TOlkien seems to make clear that "goblin" and "orc" are actually different translations of the same term. Tolkien in that letter describes where the term "goblin" is derived and in a later writting(published in The War of the Jewels(HoME XI) Tolkien makes clear that "orc(being derived from the Old English for: "Demon, Boegy"" is not only used due to "phonetic suitibility" but also due to certain, more or less, parallel definitions to primitive elvish. Tolkien says that for him "orc" and the "elvish" forms: uruk, orch, etc. do not hold any real relationship(ie the similarities in word form are only conincidences). Here is an excerpt from that letter:

Letter 144:

Orcs (the word is as far as I am concerned actually derived from Old English orc 'demon', but only because of its phonetic suitability) are nowhere clearly stated to be of any particular origin...They are not based on direct experience of mine; but owe, I suppose, a good deal to the goblin tradition (goblin is used as a translation in The Hobbit, where orc only occurs once, I think)...