The first picture above and below show that both brush sets come in a brush holder which is sooo similar, it's the same colour, it fastens the same way, as well as having the logo in the same place!
I've actually lined up the brushes exactly as they are on the Sigma website and the Six Plus Brush Set have the exact same brushes! Even the colour of the bristles are spot on with Sigmas! I couldn't believe this when I got opened the Six Plus Set, especially since the website itself sells onto companies and puts other companies logos on their products, for all we know this could be the Sigma brush set just without the logo and large price tag! As for softness, the Six Plus ones are amazing, if the Sigma ones are softer than I'd be super impressed!
The Sigma brushes retail at $120/£79 on the Sigma website but you also have to pay £11 postage if you live in the UK so that's another thing to consider, however I know there are some UK stockists so you may not have to fork out for postage.
Whereas the Six Plus brushes are $28/£18 and are sooo much more affordable if you just want to try them out and see what use you get out of the brushes and if you use them none stop then you could splurge on the Sigma ones or simply just repurchase the Six Plus ones! If you don't like the blue brushes/holder then you can also get it in purple, just simply search 'Sixplus 12pcs' on colorfulonline.com and the two different colours should pop up!
I hope you liked this kind of post, if you have any questions or any make up dupes whether it be brushes or not then please leave a comment below as I'd love to know some more!
Remember, honesty is key.
Don't forget to enter my MAC lippy giveaway here.