Acording to Alvarado Tezozomoc (a nahuatl noble that survived the conquest) in his "Mexican Chronicle" the first report Moctezuma received of the Spanish went like this (Im going to translate it, unless you want to read it in Castillian):

"... they have arrived from the shores of the great sea, in which they were fishing with nets and roads, until noon, then they entered into small canoes and reached the tall towers (ships) and reached inside..."

It continues on pointing out that they were dressed in what appeared to be ugly rags (these are macehuali speaking), that look like their ychtilmatle (a type of cloth, usually worn by the poor) and their headware that some are carrying small "comales" (pots) in the head to protect from the sun (they assume).

"... and in their flesh they are very white, more so than ours, except they all have long beards and their hair reaches to their ears".

So yeah, physically different, and somewhat alien in their cloths and appereance.