I posted Obama's chart quickly, simply because he is such a well-known figure. You are correct that his sun and moon are roughly 70 degrees apart. This is how aspects or the lack of aspects between planets are determined. We find out how many degrees separate two planets, and then:
0 degrees is a conjunction (two planets are "twinned")
60 degrees is a sextile (usually favourable)
90 degrees is a square (usually stressful)
120 degrees is a trine (usually favourable)
180 degrees is an opposition (usually stressful)
However, aspects usually are not exact. The extra room astrologers will give an aspect before ignoring it is generally:
up to 10 degrees on either side for the sun and moon
up to 7 degrees on either side for the other planets
However, some astrologers prefer wider orbs, and some prefer narrow or "tight" orbs.
Signs, houses, and house angles are not heavenly bodies, so they cast no orb. Once upon a time, signs were named for constellations, but the overlap was always only approximate, and it no longer pertains in western astrology due to the precession of the equinoxes.
Some astrologers work with so-called minor aspects, because basically you can divide the 360-degree horoscope any way you want. For example, if you divide it by 5 you get an aspect called the quintile, of 72 degrees. Barack Obama nearly has a sun quintile moon aspect: some astrologers would allow it, given that both the sun and moon are involved; others would not.
But.... we do see that Obama's sun squares Neptune, with 94 degrees of separation: a square with a 4-degree orb. His moon in Gemini squares Pluto in Virgo. (Astrodienst apparently allows a 12-degree orb for the moon, showing his moon also squaring Uranus. But note that this square is out-of-sign.)
Planets that are squared in-sign would go by the following categories:
cardinal: Aries, Cancer, Libra, Capricorn
fixed: Taurus, Leo, Scorpio, Aquarius
mutable: Gemini, Virgo, Sagittarius, Pisces
Some squares are more difficult for the individual than others. The moon and Venus are apt to be gentler. However, the closer the orb, the more the individual is likely to feel it.