[pornel]

Everything after JPEG is still fundamentally the same, but individual parts of the algorithm are supercharged.

JPEG has 8x8 blocks, modern codecs have variable-sized blocks from 4x4 to 128x128.

JPEG has RLE+Huffman, modern codecs have context-adaptive variations of arithmetic coding.

JPEG has a single quality scale for the whole image, modern codecs allow quality to be tweaked in different areas of the image.

JPEG applies block coefficients on top of a single flat color per block (DC coefficient), modern codecs use a "prediction" made by smearing previous couple of block for the starting point.

They're JPEGs with more of everything.