Hi there! The three samples would be individual pieces that you believe best showcase your work and your style. These are the pieces that the mods would refer to first during the review process, while the portfolio is meant to showcase your overall skill and ability, which would be given a less priority compared to your samples.

For example, artworks related to Raiden Ei and/or Raiden Mei would be best to showcase in your samples, while a nice background-focused artwork with other characters might be better fit for your portfolio. Hope this helps!