Galaxies vary a lot in shapes, size, color and composition. If we go for their shapes they are of three types:
1) Elliptical Galaxies
2) Spiral Galaxies
3) Irregular Galaxies
Elliptical Galaxies shapes more like a elongated sphere. Well known Andromeda galaxy is one which shapes so.
Spiral Galaxy has lot more of sections that relys of components - bulge, disk and the halo. The M100 and M83 are the spiral galaxies examples.
Irregular Galaxies has no formal regular shape or any structure. The Irr I and Irr II are some examples.
When we go through the scale it actually should start from sun which takes 8 min for the light to travel. It would actually take 17 years to get into the sun. But the scale we are taking is not about sun or planets. Its all about the galaxy which has huge distance. If the spacecraft moves fastest as 60,000 km/hr will reach Alpha Centauri Galaxy which is 4.2 light years after 80,000 years. Galaxies are that far located to imagine and have their own scales.
The galaxy scale varies from one galaxy to other. The Milky way is approximately 10,000 light years and of 9.25 $\times$ 10
km in diameter. The Andromeda Galaxy which is next to milky way galaxy is of 260,000 light years and has the diameter of 2.4 $\times$ 10
km. The popular largest galaxies are IC 1101, NGC 262, BCG of Phoenix Cluster etc which has size of (2.2-2.8) $\times$ 10