For IRS purposes, your constution and bylaws serve the same purpose as your "Articles of Incorporation". Yes, they are two different documents. However, people often have them in one word processing file or tend to refer to them as "the by laws". Unfortunately, the also sometime merge over time into ONE document.
The constitution is your organizing instrument. It has your name, your purpose, your structure, your fundamental policies for existence.
The by-laws are the rules by which you operate.
Here's a link to the on-line IRS publication about this
www.irs.gov/forms_pubs/pubs/p5570303.htm
If you are looking to create a new constitution and by laws, don't start from scratch. Get copies from schools in your area, from us on the forum, from school websites, etc. Review a few (you'll see many similarities), pick one that best fits your organization and then just tweak it. There's no point re-inventing the wheel.