I'm not very good at crochet, and I still have not finished that first bobbin lace bookmark. But I understand what the techniques are about, so I was growing increasingly surprised (and slightly annoyed) when I saw many online sellers (including the very knowledgable proprietor of Vintage Textile!) describing what I knew to be bobbin lace (even if of the machine-made-type) as crochet. Why is that? The techniques are completely different! Not only do they work in completely different ways, they usually look different.
It probably would not bug me so much if it went both ways, but it's always bobbin lace labelled as crochet. Are people simply not familiar with the technique of bobbin lace? That would surprise me with Czech sellers; bobbin lace is rather big here. (As in, traditional and admired.) Is crochet somehow considered "desirable", as opposed to bobbin lace?!
I do not want to sound like I'm looking down my nose on crochet because I can't get it right. Consider this:
This is a vintage/antique crochet trim I got from my Wonderful Crafty Grandma. (It was probably originally sewn into a bedding piece or something like that.) It's approx. 4,2 cm wide and 1 m long. All handmade.
So, yes, consider this, as an example of what crochet looks like - click on the picture to see it in detail. Of course, this is a specific style of crochet (filet crochet), and there are other ways that make it look different, with scallops and picots and what-have-you.
But it's still crochet: a technique that works with one continuous thread, working it into chains and what is called "stitches" (English sucks here; it's called "columns" in Czech, which gives you a much better idea of what it looks like). There is never, I repeat, NEVER, a simple, "unworked" thread to be seen in a crochet work.
This is a machine-made bobbin lace trim (again from my grandma). As you can see, hopefully, bobbin lace is completely different. Bobbin lace is, essentially, a type of weaving. It works with several threads and weaves them together. Sometimes it's quite open, like here.
Sometimes, there are tighter-woven motifs, like here:
But it's still very different from crochet. Simple, "unworked" threads. Weaving structure. Obvious on first sight.
The mix-up would not surprise me so much with this trim:
This is machine made just like the two examples above, and seems to be playing up to the crochet similarity. (BTW, as far as I know, there is no machine-made crochet. Feel free to correct me if you know otherwise. If you know it for a fact.) But if you look closely, you can still see the weaving structure here: there are several threads, not a single continuous one.
So here, that's the one signature difference, and now you should be able to tell crochet trim from bobbin lace.
(Note: Some types of sewn lace can look similar to bobbin lace, but those are rarer. Also, I'm only dealing with the cotton thread kind of lace in this post - I'm not as knowledgeable on the techniques involved in the making of other types of lace, like the - usually artificial fibre - stuff you find on your underwear.)
EDIT: Here are some more examples of what bobbin lace can do, from my grandma's work:
This, by the way, is the butterfly my sister wore in her hair to the Latvian exhibition opening.