There are 4 varieties of basil used in Thailand:
1. Thai (sweet) basil, horapha [โหระพา], Hung Que (vietnamese), Ocimum basilicum, Thai purple basil. => Aniseed flavour.
2. (Thai) sacred basil, (Thai) holy basil, krapao [กะเพรา], Tulsi or Tulasi (india), Hot Basil, Ocimum sanctum. =>Little bit furry. Religious use in India, culinary use in Thailand.
3. Thai lemon basil, hoary basil, manglak [แมงลัก], Ocimum citriodorum. => don't know it,but it's supposed to have a nice lime flavour.
4. Tree basil, Ocimum gratissimum. => don't know it.
Only the first 2 are readily available in the chinese supermarkets in the Netherlands.
(5. The basil, right in the photo is just our normal, everyday western basil.)