There's a lot of clothing in those pictures -- which part of it are you wondering about?

Some of the difficulty with understanding these images is that they aren't "extant". They are meant to depict the vague "Colonial" period, but were made in the late 19th or possibly even the early 20th century. What they are trying to depict has been skewed, but the 18th century terms for main garments would be a gown, which goes over a petticoat (visible at this point in the front skirt opening of the gown). The white piece at their neckline is a kerchief or neckerchief. Often a square of fabric which is folded in half to form a triangle and draped around the neck below or above the gown or jacket. It keeps the sun off or the cold out, as well as providing an interchangeable way to finish off the look. If you want to learn more about historical clothing, I'd recommend picking a very specific time frame to work on. The images you chose are meant to be three different centuries (1 & 2 are 18th, 3 is early 19th, and 4 is 17th c.) and fashion was moving fairly fast by that point. Finding dated images or original garments is also very necessary to understanding how things actually were worn. Museums are a great search engine for this, but starting out Pinterest can actually be very useful, so long as you don't assume the image descriptions are always correct (lots of modern stage costumes mislabeled).

So it sounds like you're most interested in the last image? Unfortunately, I can't find a source for it, but it looks like a late 19th century artwork doing a 17th century setting - the 1890s conception of what a "Pilgrim girl" would have looked like. So be aware that it's not really historical or traditional clothing, it's a costume.

That said, I can talk a bit about what it's based on. The ruff is a well-known piece of neckwear of the Elizabethan era - its place began to be usurped by a flat but standing/supported collar in the beginning of the 17th century, which transitioned by the 1620s into a flat "falling" collar without a support, which would rest on the shoulders. This is the stereotypical "Puritan collar" that later art and costuming would nearly always include in order to signify Pilgrimhood, though it was worn by all social levels. E.g. William Style of Langley, the Saltonstall Family. As you can see from these examples, cuffs that matched the collar were also worn by both men and women.

Are there any other specifics you're wondering about re: the other images?