Would the Franco Prussian war feature line battles akin to the ACW, or was it closer to WW1 in its conduct? I've heard von Moltke never cared much about the ACW as he saw it as using obsolete tactics and lacking any innovation
I went through my bookmarks to find threads that will help you :)
At the time of the civil war, how did the US army compare to european militaries?
How did the style of combat differ between the American Civil War (1861-1865) and the Franco-Prussian War of 1870? by /u/white_light-king
How would US troops in the Civil War era have compared to European troops in the same era (Austro-Prussian and Franco-Prussian wars)? by /u/vonadler
This last one seems to be the most pertinent to your question but the rest are informative as well.
Since I got pinged, I'd like to add a few comments.
First of all, answers or sources that site Grossman for an analysis of the ACW shouldn't be trusted. His work is highly controversial.
Secondly, there is a famous Moltke "quote": 'two armed mobs chasing each other around the country, from which nothing could be learned.' Which nobody can affirm that he actually said and provide a time and context for his remark. It's also in my opinion, highly out of character for Moltke (at least the Elder). Moltke was a highly intellectually curious professional, a student of history who cut his teeth serving in the Ottoman empire and learned a great deal from obsolete campaigns and armies. Moltke also learned a lot from studying, and taking part in, the civilian use of railroads. He didn't put the Prussian army at the peak of military innovation by ignoring everything outside of the Prussian army and scoffing at others, he was famous for leading the General Staff to compile as much information as possible. His political opponents in the Prussian army were exactly the kind of people who might have made such a sneering quote, but Moltke wasn't that kind of officer.
It is quite true that Moltke and Prussian innovations made the ACW experience less relevant. Nor did Europe in general lack for combat experience. But the architects of German military excellence weren't complacent scoffing caricatures, either.