Maaseh Yom Tov: If one transgressed a prohibition on Yom Tov, may he benefit from that item?
A Biblical prohibition: If one transgressed a Biblical command on Yom Tov, some Poskim rule it is forbidden for anyone to receive benefit from the item on Yom Tov, just as is the law on Shabbos. This applies even on the second day of Yom Tov in the Diaspora. These laws are explained in chapter 318 of Hilchos Shabbos.
A Rabbinical prohibition: If one transgressed a Rabbinical command on Yom Tov it is permitted to benefit from the item on Yom Tov. [This applies even if he did so purposely.] This however is with exception to certain Melachos which the Sages implemented a fine.
 See Beitza 17b; Piskeiy Teshuvos 495/2 footnotes 5-16; Nitei Gavriel 44/1; Yom Tov Kehilchaso 1/61
 Taz 503/1 regarding fire; P”M 495 Pesicha Koleles 2/5 [although is possibly lenient in a case of great loss]; P”M 503 M”Z 1 that so applies even according to Rashba; Shut Magidos 110; Implication of Rashi Beitza ibid; See Tosafus and Ritva Eiruvin 41b; Rashba 42a; Piskeiy Teshuvos 495/2 footnote 5; Yom Tov Kehilchaso 1/61 footnote 162
Other opinions: Some Poskim learn that the Sages did not fine against benefiting from even Biblical Melacha performed on Yom Tov. [Possible way of learning Admur and all Poskim brought in coming footnotes who are lenient regarding a Rabbinical prohibition; See Nitei Gavriel 44/1; Piskeiy Teshuvos ibid footnote 5]
 Rav SZ”A, brought in Yom Tov Kehilchaso footnote 160
 Admur 502/1 regarding fire; 503/13 regarding cooking for next day; 505/5 regarding milking cow; Elya Raba 502/2; Beis Yosef 503 in name of Rashba 5/8; Michaber 503 and 527/23 regarding one who transgressed and cooked for next day; Shevet Halevi 6/68
Other opinions: Some Poskim rule the laws of one who transgressed a Rabbinical prohibition on Yom Tov follows the same laws as Shabbos. [Implication of Taz 503/1; Rambam Shabbos 23/15 regarding Teruma; Rosh Yosef Beitza 4a; Toras Shelamim Y.D.D 197/3; See lso Rashba in Avodas Hakodesh 3/4; M”B 506/20 regarding Teruma; Biur Halacha 527/23 “Im Avar”; Rav SZ”A; Betzel Hachochma 5/94; 6/5; See Piskeiy Teshuvos ibid; Yom Tov Kehilchaso 1/62]
 The reason: As the Sages did not fine one who performed a Melacha on Yom Tov to the same extent they gave a fine to one who did a Melacha on Shabbos, which is more severe. [Admur 502/1] The Sages did not desire to give a fine on Yom Tov prohibitions which are light, and rather only did so for Shabbos prohibitions which are severe. [Admur 503/13]
 See Admur 339/7; 405/9 from which it is implied that even on Shabbos, if it was done Beshogeg it is permitted, and hence if Yom Tov is more lenient than Shabbos in this matter, it must be referring to a case of Bemeizid.
 See Admur 503/12 regarding cooking in a way of Harama; 515/1 regarding one who brought food from outside the Techum.