Reduce means to use a material/commodity in lesser quantity,
e.g electricity and water
Recycle means a material that is used once is collected and sent back to a manufacturer so that they can make some other useful material from it:
e.g., plastic cups and buckets, glass tumbler, paper, metal objects
Reuse means using a thing over and over again instead of throwing it away. It does not involve the process of recycling either in small or large scale:
e.g., used envelopes, plastic carry bags, bottles of jam.