This is a category where the names get used loosely and the differences are real. Worth ten minutes before you spend.
The four things, and what they actually are
Scarf
Long and narrow. Goes around the neck. Its whole job is to sit close and be soft, which means fibre fineness matters more here than in anything else you will buy. A scarf touches the side of your neck, which is some of the most sensitive skin you have.
Wrap or stole
Wider and usually longer. Can go around the neck like a scarf or over the shoulders like a small shawl. The most versatile thing in this list and the easiest to buy as a gift, because there is no size to get wrong.
Ruana
A rectangle with a slit for the head, open down the front. It hangs like a long open cardigan and it is not a poncho, which is closed. The ruana is the South American original and it is the most wearable of the lot for anyone who does not like things over their head.
Cape
Closed at the front or fastened. More formal, more of a statement, and the one most likely to sit in a wardrobe if it does not suit your life. Buy a cape because you want a cape, not because it was on sale.
What to look at
Fibre fineness, especially in a scarf
Comfort against skin comes down to fibre diameter. Fine alpaca sits well below the roughly 30 micron point at which fibres start to feel prickly, and its surface is smoother than wool's, which is why people who find conventional wool scratchy often get on with alpaca. That is not a guarantee for every person with a fibre sensitivity, and if you are buying for someone sensitive, a test against the inside of the wrist is worth more than any description.
Drape
Alpaca's real strength. It hangs rather than bounces, which is exactly what you want in a wrap or a ruana and completely irrelevant in a beanie. Hold a corner up if you can. Good alpaca cloth falls in a soft curve rather than sticking out.
Weight
A light wrap layers under a coat and travels well. A heavy ruana is a garment in its own right and will not fit in hand luggage. Decide which you are buying before you compare prices, because a heavier piece contains more fibre and should cost more.
Finish
Look at the edges. Fringes should be even and secure. Hems should be flat. This is where cheap production shows first and it is visible in a decent photograph.
Colour
Natural undyed alpaca comes in white, fawn, brown, grey and black, and the depth in a natural dark shade is something flat dye rarely matches. A black ruana in undyed fibre has a charcoal complexity in the light that a dyed one does not.
Against that, dark colours hide texture. If a piece has cables or an interesting weave, a pale fawn or grey will show it and a deep black will swallow it.
Sizing, or the lack of it
The practical advantage of this whole category is that almost none of it has a size. Scarves, wraps and ruanas fit essentially everyone, which makes them the safest alpaca gift there is. Capes are the exception and do have a fit.
Care
Hand wash cool with a wool wash, do not wring, press the water out in a towel and dry flat away from direct heat. Store folded rather than hung, because hanging stretches the shoulders of anything knitted. Air between wears rather than washing.
Ours
Our scarves and capes and ruanas are made from genuine Peruvian alpaca, where this kind of garment has been made for generations. They are not made from our Mulgoa herd's fibre, and we say so on every page. Our own farm fleece goes to hand spinners.
See also: choosing alpaca wool that feels as good as it wears.