Ranking for similar long tail keywords

Fairly new to SEO and learning as I go for our small local family-owned service business. My question is about similar long-tail keywords. As an example is we are ranking in the top 10 consistently for the long-tail - photo booths for rent does that mean that we will eventually just organically start ranking for photo booths to rent or do we need to target each phrase as individual ones.

I only ask because we have ranked in the top 10 for weeks for 1 but don't even rank in the top 100 for the other, it makes no sense to me, what am I missing?

Thanks in advance for any advice