In English, there are twenty-four different consonantal sounds altogether whereas Thai covers
only twenty-one sounds. These do not include clusters.
While most English consonants belong to fricative, Thai consonants are mostly grouped in
plosive. As for the sound [r] or "ร" in Thai, it is classified as voiced retroflex approximant, but Thai
regards its "ร" as voiced alveolar flap. And it is the nature of Thai not to use "dental" as a place of
articulation, so [P] and [D] do not exist in Thai, either.