There is a difference between every reader. You should try a few and find out which one works well for you.
But yes, there is no fundamental difference between free and paid. For hosted readers free will often have tighter limits on the number of feeds you can follow and how often they update. They may also provide add-on features such as summarization and automatic organization. For local readers paid readers may just have features disabled until you pay.
Is there a big difference between paid and free readers? It seems weird for them to only list readers with monthly cost (+a browser).
There is a difference between every reader. You should try a few and find out which one works well for you.
But yes, there is no fundamental difference between free and paid. For hosted readers free will often have tighter limits on the number of feeds you can follow and how often they update. They may also provide add-on features such as summarization and automatic organization. For local readers paid readers may just have features disabled until you pay.