Grosgrain ribbon (as pictured) is a very versatile ribbon, ir is easily recognisable by its distinctive ribbed texture. Grosgrain is a stiff versatile ribbon which makes it great for crafting, it can be used for anything from home decor projects to dress making, a very common use is for making hair clips and its stiffness is great for holding the shapes of bows and is also thicker and more durable which makes it great for projects that will be handled. Grosgrain ribbon comes in varying widths, common sizes being 3mm, 9mm, 10mm, 16mm, 22mm, 25mm, 30mm, 50mm but can be found in various other sizes online, in craft shops or in fabric shops. You can find grosgrain ribbon in just about any colour you can imagine and you can also get patterned/designed ribbon (as pictured) which is great for bringing a piece of work to life. My main tip would be do kot be afraid to ask the sellers any questions you may have and also do not be affraid to buy from overseas the quality is amazing and although it can take a couple of weeks to arrive it is a lot more cost efficient so if you have the time is it definitely worth waiting for. The more pennies you save the more ribbon you can buy :)
Silk ribbon has a more luxurious feel and look to it and it's great for adding a bit of prettiness to any design, however I would not recommend for all crafts, it's great for detailing on clothes, jewellery making, or card making or for even making a pressies look that little bit more special with a luxurious bow, but it is not so great for things that need to hold their shape a bit more like hair clips and its is easily flattened as it also easy to catch and fray. Silk ribbon is also best used with a more gentle adhesive so if your planning on using something like a hot glue gun I would stay clear of silk as you will be able to see the glue underneath the ribbon. Silk ribbon mainly comes in plain colours but as above the options of colours are endless and also the width of the ribbon again can vary greatly. Again also I highly recommend buying from overseas if you have the time but can also be bought from craft or fabric stores. Sometimes even large supermarkets may stock some silk ribbon, silk ribbon is definitely easier to get your hands on.
Both ribbons are great for different things, my verdict would be if you are crafting and need some strength or durability or would like a more fancy style ribbon that is easy to you and a bit more forgiving (great for crafters just starting out) then I would highly recommend grosgrain ribbon, however if you are looking for something with a fancier prettier look that has more of a free flow to it which is great for hanging or making necklaces for example then silk is the ribbon to go for. Both great ribbons but great for different uses.