Chutney comes from the Indian "chatni", which means "strongly
spiced". Normally, it is made out of fruit pieces, vinegar, sugar, peppers
and/or other spices.
Chutney is nice with Indian food but also as a replacement of mustard with
cheese.
According to this definition, the coriander chutney is not a chutney at all
(no sugar, no cooking), just a sauce, but still, this is how it is known.
Relish is more or less the same as
chutney; the cooking time may be a bit shorter though. Therefore, chutney is
normally softer and the sugar may be caramelized.
Salsa has most probably an Aztec Indian background and is made of tomatoes and
chillies as main ingredients. Salsa means "sauce". Salsa is cooked shortly and
is not sweet or caramelized.