As far as I can tell Hardcore mode is the same, except 1 death = you've to restart from the beginning.
I got a Titanium sword and Iron Shield thinking I'd be kicking butt against the guys that are beyond the snakes' and slimes' areas, they still whooped me. Often when I'd attack any enemy my character would turn red and not attack when they got near to the enemy, letting the enemy hit me. Not sure why that happened, maybe it's an intended feature.
I ended up stopping after losing my Titanium sword randomly upon death in that area. Yeah it wouldn't be too hard to go fetch it, but I've grown tired of the game now.
I'm not sure what the best money maker would be, I'd guess crops but I didn't bother with them (the whole process didn't appeal to me after a couple small harvests), opting for foraging. Seemed like enemies got pretty tough in areas where I was looking for some of the more valuable ore, and the ore seemed somewhat scarce. Was a bit of a grind since I didn't want to spend the ore on upgrading the hammer, opting for my weapon first.
Maybe the more valuable seeds/crops would have a big payoff. You also have to use season specific seeds. Pretty good game, though I found it a little slow for me. When I was a lot younger Harvest Moon appealed to me, but I think I've grown more impatient since then.