Google AI gives this information when using 'lintel and header' as the search text... even going as far as to suggest it will help give 'best building practices' depending on what you're building

C&P (copy & paste):
AI Overview
View attachment 55202
Both
lintels and
headers serve the exact same primary purpose: acting as horizontal support beams over openings (like doors and windows) to safely transfer the weight of the structure above to the vertical supports on either side. However, they differ significantly in their material and typical construction application. [
1,
2,
3]
1. Construction Style
- Lintels: Primarily used in masonry and brick construction. They sit across the opening in a brick or block wall to carry the weight of the bricks above. [1, 2, 3]
- Headers: Exclusively built into timber-frame or light-gauge steel wall construction. They frame out the rough opening for a door or window and distribute the vertical loads to the surrounding studs. [1, 2, 3]
2. Materials
- Lintels: Generally crafted from heavy-duty, rigid materials like precast concrete, cast stone, or structural steel.
- Headers: Usually made of doubled-up timber framing lumber (e.g., two 2x8s or 2x12s sandwiched together) or engineered wood, often concealed by drywall. [1, 2, 3]
3. Visibility and Aesthetics
- Lintels: Because they support exterior brickwork, lintels are frequently visible and sometimes designed to be ornamental.
- Headers: Because they function inside interior or exterior timber stud walls, headers are typically hidden behind siding, drywall, or other finish materials. [1, 2, 3]
Summary Resources
While the terms are often used interchangeably by laymen, understanding the difference comes down to the building method. To explore the engineering distinctions and building terminology in more detail, refer to resources like the
Lintels vs. Headers Guide on Extech Building Materials or the
Design+Encyclopedia Lintel Vs Header page. [
1,
2]
If you are working on a specific building project, let me know:
- Is the wall made of timber (wood) frame or brick/masonry?
- What is the width of the opening you are trying to support?
I can help you narrow down the best building practices or standard sizes needed for your build!