Let's look at the definitions of the two.
Denim, officially known as Denim fabric, is a thicker, color-woven warp twill cotton fabric. The warp yarns are dark in color, usually indigo. The weft yarns are light in color, usually light grey or boiled down to a native white. Denim, also known as indigo labor cloth, began in the western United States, where ranchers used it to make clothing and trousers. The warp yarns are dyed in one step using a sizing and dyeing process. The warp and weft are high, usually with 3/1 tissue, and the texture is tight and thick.
Chambray is a cotton fabric with a single-colored warp, a bleached weft, a bleached warp, and a single-colored weft. Chambray fabrics are mostly used for casual wear. The color is mostly medium, i.e., the darker warp (or weft) and white weft (or warp) yarns are interwoven, but the color on the surface is still medium to light. The cloth surface has a two-color effect, and the fabric has a harmonious color palette, is light, smooth, and soft, and is named after its suitability for young people's clothing. Chambray fabrics are often used for shirts, shoes, hats, lingerie, home textiles, and quilts.
These definitions are true in themselves, but the processes of our textile products are also variable, so it would be easy to enter into several misconceptions based on the above alone, as follows.
Correction: This understanding is correct in the traditional sense, but denim is also available in plain and chambray in twill. As shown in the picture, the left is a cotton twill chambray, and the right is plain denim, also known as reversible denim.
Traditionally, chambray is mainly plain, but some chambray products are becoming more and more "denim-like". This part of the chambray is mainly in blue, navy, black, and other colored yarns, with a 2/1 or 3/1 twill weave to deepen the color of the front of the fabric and bring out the denim-like style.
Correction: This perception was probably true at the beginning. Nowadays, however, denim can be thin, and chambray can be thicker, so there is no clear distinction between making tops or trousers. For example, on the left is a 16S linen-cotton blend encrypted thick chambray and on the right is a 21S Tencel chambray, for both of which the former is more suitable for trousers and the latter for shirts.
Correction: It should be easy to change the color of the yarn, as the chambray was originally bleached. But nowadays, they are also available in natural white and even in colored spun yarns. In the picture below, if you look closely, the white yarn of the blue youth cloth is whiter than the white yarn of the dark grey youth cloth, which is made of a native white yarn, slightly yellowish, revealing an antique style.
The world of fabrics is a huge market with a huge variety, so there is no need to be overly cautious. It is not our intention to make a comprehensive comparison between youth and denim, from yarn dyeing to garment making. Still, the main difference between the two, in terms of summing up our daily production and processing experience, is whether they can be washed and faded. Denim can be washed or sand-washed to produce a certain amount of fading. Chambray is a purely color-woven fabric and does not fade with regular washing.
From top to bottom, the first three colors are all 'washed' from the same dark denim (i.e., the bottom one), as shown in the picture. Denim can be washed in different shades of color and more by controlling the wash/sanding level and process. This is the 'wow factor of denim so that each pair of jeans is unique because the longer they are worn, the more they are washed and worn, the more they will naturally give off the smell of age.
Therefore, denim is washed and stonewashed to create a faded effect and a frosty white look on the fabric before it is made. In contrast, chambray is generally washed after the garment is made to complete the pre-shrinking of the size and remove any hairballs on the fabric. In the picture below, the left side compares blue chambray before and after washing, and the right side compares navy twill chambray before and after washing.
The wash and fade effect of denim makes it very popular for jeans made for casual wear. However, it is more business-like and formal in the workplace, so chambray with good colorfastness and a faux denim style has gained favor, and the high-count, high-density chambray is more business-like than the low-count one. The advantage of the two-color effect on the fabric has developed more colors, styles, and techniques. It is gradually making its mark in shoes and hats, bags, homes, stationery, and automotive products.
Finally, as a joke, if you happen to come across a chambray that fades when washed, chances are that you are mistaken, and it is denim, or of course, a chambray that does not meet the color fastness standards.