Original: In the United Kingdom and Ireland, the heatless varieties are called "capsicums", "sweet peppers" or "peppers" (or "green peppers," "red peppers," etc) while the hot ones are "chilli/chillies" (double L) or "chilli peppers".
Simplified: In the United Kingdom, Ireland, and Canada, the heatless varieties are called "peppers", "sweet peppers" or "capsicums" (or "green peppers," "red peppers," etc) while the hot ones are "chilli/chillies" (double L) or "chilli peppers".