Sage Mode is part of the Sage Arts.
Originally Posted by knife eater
Sage Mode - a way of engrossing oneself in/with natural energy.
Sage Arts - an art/technique of using natural energy.
You don't need to be in Sage Mode in order to use Sage Arts, but Sage Arts are much more effective in Sage Mode.
I'm not sure what do you mean...?
Wait, are you implying that Hashirama normally has tattoos on his forehead, around his eyes and all over his face ? He is still shown gathering energy, it's just that he has a different position, it's possible that Jiraya as well took a different position in order to gather Natural Energy, from the one that Naruto takes. Basically, it doesn't matter what position they take, as long as they are truly motionless.
...maybe, I'm not sure, since Hashirama already has the 3rd legendary Sage Mode, so well it... no I take it back :P. I almost forgot that each of the Sage Mode types had at least 2 known users in the series (Frog: Jiraya, Naruto; Snake: Oro, Kabuto: 3rd: Hashirama, Sakura?/Tsunade?).
I guess that the fact that Haruno clan symbol is exactly the same like the one that appears on Hashirama's forehead when he enters Sage Mode, can mean something and there might be a connection. Still, seeing as neither Jiray nor Oro had a perfect Sago Mode (though Jiraya went further with his studies in this regard) then the same would mean for Tsunade and seeing as Hashirama has a perfect one, Sakura's might not be a perfect one (I would rather like to see her Supreme Chakra Control to play again, but not like Tsunade, to heal, but one that condenses her chakra - similar like in the fist but better - into each of her cells, making her pretty much Ultra Human surpassing those with Super Human Strength).
Now that I mentioned Sage Mode types, then assuming that there are only 3 and that 4th Kazekage's marks weren't an effect of the Kekkei Genkai, then I would have to say that Garaa and his Dad are blood related to Jyugo's clan, but their effect is very limited and only effects appear around their eyes (this means that Garaa is constantly using a bit of Natural Energy or something like that, plus Garaa's red hair is a prove of being Uzumaki so this goes quite nicely with his capabilities in this department).
you can go back and argue about the eye appearances between contracted summoner and affiliate animal but after 642 we have a clench. for instance, the frogs have their eyes because of of their intake of natural energy, it just so happens that kishi made that the standard for the mountain frogs.. you cannot divorce the two so easily. naruto takes his sage mode eyes in the appearance of frogs eyes for both reasons of frog affiliation and natural energy influence, the two are not so easily divorced. typical jutsu by frogs are senjutus, which was never before confirmed.
senjutsu seems to be wielded at different levels of awareness by different users. they do not necessarily require the conscious gathering of natural energy even though natural energy will be a component anyway. the technique may be used without the user even knowing or understanding the presence of natural energy.
senjutsu+ (i get the literal translation goes back to senjutsu but in english we have the benefit of distinction) are the conscious use of natural energy in senjutsu. they may not necessarily require the user to be in sage mode because it may be possible to harness the natural energy for the senjutsu in a less direct manner than molding it while in sage mode.
sage mode is making the user's body itself reactive to natural energy for sake of gathering to mold into enhanced ninjutsu, senjutsu or other local benefits like healing or enhancing strength.
i still believe tsunade's genesis technique is a senjutsu.
hashirama appears to use senjutsu out the ass. his body heals without seals and he develops the markings associated with sage mode though not 100% confirmed (95% certainty?) hashirama may even be in a sage mode but whether it is more crude or advanced than jaraya/naruto sage mode is not known. maybe with different restrictions/advantages (can he move as he gathers without help of clones?), tsunade's regeneration is a branch of some of hashirama's senjutsu
orochimaru probably uses senjutsu without sage mode
kabuto can definitely use sage mode senjutsus but maybe does not know senjutsus that are not sage mode dependent
sakura can use the tsunade variation
sasuke likely does not yet know any senjutsu, he cannot enter sage mode (strongly implied unless super twist) but the lightning strike against itachi during their battle was a strong allusion to natural energy and its relationship with ninjutsu. some people dismiss this picture but to me it is saying loud and clear nature+jutsu, a good foreshadowing of sasuke's future senjutsu use.
if we go back it appears there are quite a few instances where a technique may be a type of senjutsu. maybe others can dig for examples like the post refering to gaara and his father above me. i do not believe in the juugo connection, however.
my impressions after 642