The specification sheet is commonly referred to as 'Spec Sheet'. The spec sheet is a component of the Technical Package (Techpack), where the Techpack contains absolutely everything required in making the garments - in the sampling stages, in bulk production, in finishing, and in the packing garment. 
To develop a garment sample, you need a full techpack. The spec sheet contains part of tecpack information, mainly the technical sketch of the garment and measurement chart for multiple sizes with grading and measurement tolerances.
Content of a Techpack
In the fashion industry, the spec sheet and techpack are created by the designer or the product developer.
Though sometimes we use spec sheet and Techpack terms interchangeably, these two terms are different. To differentiate these two terms we can use the following parameters.
To develop a garment sample, you need a full techpack. The spec sheet contains part of tecpack information, mainly the technical sketch of the garment and measurement chart for multiple sizes with grading and measurement tolerances.
With a spec sheet, you can only make the garment patterns and check garment measurements.
Contents of a spec sheet and Techpack
By going through the contents of the spec sheet and Techpack, it would be more clear to you.
Content of a Spec Sheet
Related post: How to make a spec sheet for an apparel item.
Content of a Spec Sheet
- Product Code (Style Number For Fabric And Fabrication)
- Product Description
- Technical Sketch
- Detailed Measurements
- Placement Details
- Materials and Trims
- Reference Materials
- Graded Spec
Related post: How to make a spec sheet for an apparel item.
Content of a Techpack
- A Pattern
- Testing Details (FPT and GPT requirement)
- Costing Details
- Quality requirement
- Technical sketch
- Workmanship and stitching instructions
- Sample of Fabric, colour combination for trims for different base colours
- Packaging Information
- Bill Of Material (BOM)
- Updated with comments on garment samples submitted to buyers. Mainly size set sample and PP sample comments.
- Some buyers also include mini marker and fabric consumptions in the apparel techpack
Conclusion
It is advised to use the correct term when you are communicating with the internal team and with your buyers. Remember, the Techpack can be called a spec sheet, but a spec sheet can't be called a Techpack. The reason, the spec sheet does not have all the information a Techpack should have.