What is the difference between Tiffin and Breakfast ?

Tiffin can be any light meal. Originally it meant what the English call afternoon tea.

Tiffin is a form of cake-like confection composed of crushed biscuits (most commonly digestive biscuits), sugar, syrup, raisins and cocoa powder, often covered with a layer of melted chocolate. Unlike regular cakes, Tiffin does not require baking. Instead, following preparation of the mixture, the confection is chilled until set. As a consequence the product may also be known as 'fridge cake' or another similar term. It was invented in the early 1900s in Troon, Scotland.

The confectioner Cadbury produces a chocolate bar called "Tiffin", consisting of biscuit pieces and raisins in chocolate, as part of its Dairy Milk range.

https://en.wikipedia.org/wiki/Tiffin_%28confectionery%29

https://en.wikipedia.org/wiki/Tiffin

A lunch, or slight repast between breakfast and dinner; -- originally, a Provincial English word, but introduced into India, and brought back to England in a special sense.

http://machaut.uchicago.edu/?resource=Webster%27s&word=tiffin&use1913=on

tiffin

a light meal, esp one taken at midday

http://www.collinsdictionary.com/dictionary/english/tiffin

https://www.wordnik.com/words/tiffin

More than any other word, tiffin, meaning lunch or any light meal, evokes British India.

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http://www.worldwidewords.org/weirdwords/ww-tif1.htm

tiffin

A light meal, especially lunch.
Example sentences

The business of delivering dabbas - also known as tiffins, from an Anglo-Indian word for ‘lunch’ - began more than a century ago, reputedly at the request of a hungry English administrator.
And despite our objections, they brush the dust off our feet, fan us if we are looking hot and share their tiffin with us.
From an all-time tiffin to a filling meal, dosa has made a place in the heart of gourmets across the country.

http://www.oxforddictionaries.com/us/definition/american_english/tiffin

http://www.thefreedictionary.com/tiffin

Origin of TIFFIN
probably alteration of tiffing, gerund of obsolete English tiff to eat between meals
First Known Use: 1800

http://www.merriam-webster.com/dictionary/tiffin