Which board you choose really depends on the sort of design you're doing.
Generic answers like this one really do not help at all. And more so when specific questions were asked.
I was asking what is the difference between MAX10 and Cyclone 10 LP family and what is difference between those boards. To me they look the same except # of LUTs. How can I choose one based on planned design if I don't know the difference?
Let me copy/paste questions again:
Is 8k LE vs 25kLE the only practical difference?
Which FPA family is newer or has faster fabric?
Has one of them better chance to get supported in opensource toolchains (yosys, nextpnr) or at least have better linux tools support?
Is there something specific one of them has and the other doesn't?
It is OK to not answer if you do not know :-)
My point was this, and it directly addresses your questions.
If you only need 8k logic elements for your design, you can choose either part. If the design is larger, you go with the larger parts.
Whether a family is newer or not only matters if the tools don't support it, or whether the newer family has a feature your design requires.
Which family is faster doesn't matter if both meet the timing requirements of your design. If one doesn't meet those requirements, it's not up for consideration.
Re: open-source toolchains -- no. Linux support? Check the Altera/Intel web site.
Whether there is something specific one has and the other doesn't only matters if your design needs that feature.
Does this clarify why I said your choice is driven by your design requirements?