Bottom Line Up Front (BLUF): Suno V4.5 is the base model of the 4.5 generation. It already writes songs with vocals and lyrics from a short description, suits simple tasks well and remains the most affordable of the 4.5 versions.
V4.5 confidently makes typical songs: a chorus, verses, a clear melody. It does not follow complex descriptions as subtly as V4.5+, but it handles basic genres without any setup.
If you need a song from a single phrase and do not care about fine arrangement details — V4.5 is cheaper and more predictable than the bigger models.
The plus version follows detailed descriptions and complex arrangements more precisely.
Yes, custom mode lets you use your own lyrics and style.