Finer detail and faster motion is better captured in 1080 60p. The "p" means a full frame is captured with 1080 lines, 60 times every second. It is a current standard for HD TVs now on the market.
1080 60i is a "lesser" format where the "i" means "interlaced. In some ways it can be considered as left over from the beginnings of TV. When TVs were fat and slow, it worked best to display every other line, and then, the next "interlace" all the other lines. The eye didn't notice and transmission required less bandwidth.
It seems that many videos find their way to YouTube and Facebook and never get shown on a current flat screen TV. Various conversions take place for that. So, again, the eye will probably not notice.
Still, many vidographers think that important footage should be captured in the best possible format as the "original". Then, with software, various copies are made for the target. Typically, most editing software that makes high quality Blu-Ray discs will convert 1080p to 1080i!
Depending on equipment, 1080 60p files can be difficult to watch in their 60p original version.
Given the two choices, I would buy the Lumix.