With direct to garment (DTG) printing, ink is applied using inkjet technology directly onto garments such as t-shirts. Because this process uses a printer, it's possible to achieve a lot more detail than traditional screen printing methods. In addition to detail, merchants have a lot more color options because an inkjet printer can print multiple colors as easily as a single color.
With sublimation printing you can achieve vibrant and highly detailed results, but you are limited to material choices being able to print only on 100% white polyester or polymer fabric.
In general, compared to screenprinting you can expect:
Larger color variations
Slightly less vibrant colors (unless using sublimation)
If you are printing lighter colors on darker fabrics with DTG, you may see some ghosting around the design from the white underbase. This is typical.