In Spanish, these two letters have almost the same sound in almost any syllables where them are used. The “B” or “B labial (with the lips)” (pronunciation based on the union of both lips) and the “V” or “V labidental (with lips and teeth)” (pronunciation based on the union of the upper teeth with the lower lip), have similar sounds when they are used in everyday speech. For this reason, the understanding of the construction of Syllables in Spanish with these two letters is very important.
However, the replacement of one by another when writing, is considered one of the spelling errors more notables of the language, and when spelling words is remarkable the use of one or another, to the point that, in the universe of Spanish-speaking, is usual the question:
With B of Burro (donkey) or with V of Vaca (cow)?
Simple syllables in Spanish with the 5 vowels are, for the “B”:
and for the “V”:
The practice of these sounds is important to “mentally set” the difference between both languages. Remember (it will be repeated many times) when beginning to speak in Spanish, MUST forget about the pronunciation in English, because although both languages use practically the same alphabet, the sounds are VERY different. Then… To practice!