In Western tropical astrology, the zodiac circle is divided into twelve equal sections of 30 degrees. The count begins at the spring equinox; Aries is the first section. Astronomical constellations are regions of the sky with defined boundaries. They are not all the same size, and the Sun spends different amounts of time against each constellation. Its apparent path even passes through Ophiuchus, which is not part of the familiar set of twelve signs.
There is another difference over time. Earth’s axis slowly changes direction, so the equinox point shifts in relation to the stars. A tropical sign remains tied to the equinox, while a constellation refers to a particular region of the celestial sphere.
So “the Sun is in Aries” in a tropical horoscope does not claim that a telescope will show it among the stars of the constellation Aries. When checking such a claim, first ask: are we talking about a sign or a constellation? They share names, but use different coordinate systems.
The stars speak. The choice is yours.