Playgroups are usually non-profit and may be run by volunteers including parents. They may or may not be open all week.
Nurseries are either private or attached to schools. Apart from 15 hours of free learning per week after your child is 3, you have to pay for nurseries. School nurseries are open throughout the school year and private nurseries are often open all year.
Reception is the first class in primary school, before Year 1.