Even people can think their business is the same, just with videos instead of music, the truth is that the focus of Netflix is way beyond what Spotify offers. This is why I would rather invest in Netflix than Spotify, even more, I don't think Spotify will finish the decade if not under a bigger company.
For finding the reason, as always, I won't step into graphics of price target but rather more into logic and business analysis. What both companies offer are streaming services with a monthly fee that give you free access to all the content. For Spotify and the music industry, this service means one way of stopping piracy and a way to offer all the content you can imagine (as only some artists, albums and discographic are not in Spotify). But this means that the content they are offering is also available in other streaming services such as iTunes (where you can also buy albums, I still can't understand what for) and Amazon Music, where it seems that all the music you want to hear is not available for free… another reason why Spotify is still the best of the three for the moment.
But the truth is that for using Spotify you don't have to pay, you can also stay with the free use version that will annoy you and your guests (and sometimes your customers) when every two songs an add jumps to your speakers. On the other hand, for using Netflix you have to be registered and even if you are sharing your account with another 200 people all over the world you will be limited in use.
Until here the one clear and easy difference between both, but the real big deal comes now. Netflix generates content, Spotify not. So while Spotify gets all the music available all over the world and tries people to listen to podcasts (something that Apple has been doing for a very long time), Netflix is generating new content that is not available on any other platform. And the content is getting so good that they have even won some Oscars in recent years.
Until now the income and money making from Netflix has been only the users paying their monthly fee but not far from now they will for sure start selling their series and film to be seen in open channels or other platforms, meaning this that their income will no longer be from one side (customers) but from both sides (customers and product).
This model reminds me of Tesla business making with their Supercharger Network, where for now they only offer it to customers, but for sure they will open it to the general public once their customers and market ownership is big enough not to worry about the competence. The same will happen with Netflix, even if other channels are offering great money now it doesn't make sense to win “some money” by selling rights when they can “get customers” that once they have watched the content and have been “the first ones” won't really care if it is being open to watch in other channels. Timing is everything.