Pressing vs Ironing- Knowing the DifferenceLet's start with some basic definitions. Ironing is to smooth (clothes, sheets, etc.) with an iron by moving it across the fabric. Pressing is to apply pressure to flatten, shape, or smooth fabric, without moving the iron. Now, let me explain further.
In the sewing world, this is typically the goal during garment or quilt construction. When pressing a piece of fabric or garment, the iron does not move while it is touching the board. It's a press, hold, lift technique. What this accomplishes is the smoothing and/or creasing of the fabric without the pull that could possibly distort your pieces. Pressing is what you want to do with cut pieces, uncut fabric, opening seams, creating a memory hem, etc.
Another common use for pressing is to create a crisp crease in a finished garment or when creating things like box pleats and pin tucks. It can be especially helpful to keep a can of spray starch nearby when attempting these as it will stiffen the fabric and hold those creases amazingly well.
Ironing is best saved for the finished product. Once the garment is completely sewn, there is less risk of distorting the fabric when moving the iron over it. Ironing is a great way to get the final wrinkles out of your finished garment to prepare it for wearing or photographing. It is essential in the finishing of ALL garments, including knit ones. It creates a nice clean crisp end product that will have everyone asking where you bought it.
Final TipsWith both of these iron methods, you want to be sure your iron and board are clean and that your board has sufficient padding. It will help your end result immensely. Also, do NOT use flavored water in your iron! I've heard of a few people doing this as a "life hack", but I can promise, the only thing this will accomplish will be to ruin your fabric/garment AND your iron, and you don't need that headache in your life, I'm sure.
Now that you know the difference, use the knowledge well. And Happy Sewing!!!