Every language has words that sound the same. For the most part, Spanish words such as "callado" and "cayado" sound the same. The old LL-sound is all but extinct now. "Hola" and "ola" offer a more typical example of the same phenomenon. In English there are countless homophones. We should be aware of them so that we do not try and make nonexistent differences.
Patética Fonética 2.10. Things that are not pronounced. Part 1
Some students are obsessed with pronouncing everything they see or everything they hear. The truth is English spelling offers plenty of examples of letters that we are NOT supposed to pronounce. There are also many cases in which natural diction calls for some degree of sloppiness.
English is full of consonants. This presents something of a challenge to those native speakers of Spanish who, in their own mother tongue, find it difficult to pronounce terms as innocent as "monstruo", "taxi" or "alumna".