There IS a difference between white passing, light skinned, and racially/ethnically ambiguous guys.
White passing is when someone is a person of color but are practically indistinguishable from a white person. Some white passing ppl are even blonde haired and blue eyed, but are still technically not white.
Light skinned is typically used when someone is clearly not white, usually because of their features, hair, etc. But still have lighter skin than usual.
And Racially/Ethnically ambiguous is when someone is once against still clearly a person of color but their race or ethnicity is still very unclear from their appearance, they can be light skinned but can also be dark skinned too.
Y'all (usually white ppl) really should learn these terms and what they mean before you just toss them around or ascribe them to yourselves (eg. A white person isn't light skinned, just white)
I also kinda resent how popularized the term "white passing" had gotten in recent years.
So often it's used by someone who is white but took a 23&me test to find out they're like 5% non white or something and do nothing of connecting or contributing but just call themselves white passing PoC to talk over actual PoC.
"White passing" as it's used now is a case of AAVE dilution via social media & non-Black misinterpretation, as well as a general lack of contextual knowledge among younger people spreading it.
The term was initially a very specific, deliberate, active verb: when a Black person who is both ethnically ambiguous AND light-skinned enough to be indistinguishable from a white person to white people (this is important— many Black people "pass" outside the Black community but are clocked by other Black people, esp ones used to seeing the difference between white & "lightskin" features; some white communities regionally or culturally are more oblivious than others with regards to white lightskin or mixed race Black people look like to begin with, ie whitepassing in MA is not necessarily the same as whitepassing in GA or CA or HI), chooses to "pass" and live their public + sometimes private life as a white person, whether for survival, social, or financial benefit. It carries baggage of assimilation, cultural & historical erasure, and isolation— because attempting to leave behind one's race means leaving behind one's family & loved ones as well.
This goes all the way back to "tragic mulatto" tropes, and is a dramatic hallmark of older Black fiction & early Black cinema. Sometimes it's played for tragedy, where a person can't grieve Black relatives who've died without shattering the ruse, sometimes it's a dramatic plot twist à la "Devil In a Blue Dress," sometimes it adds tension to a narrative: will a whitepassing bastard son inherit, will this person be able to go to college, can this character hide their brownskinned siblings or parents by pretending to be a slavemaster themselves?
It's also understandably got a very messy legal history, and THAT goes all the way back to at LEAST Spanish colonial presence in the Americas + the very beginning of the "New World" Trans-Atlantic Slave Trade, and what limitations were placed upon Blackness & Black people in the first place. Even early anti-miscegenation law would allow marriage annulments & property seizures just on the implication that a spouse was hiding Black ancestry, judges would "inspect" accused women's nipples & genitalia in court for signs of "Blackness" vs "whiteness" to determine if their husbands were allowed to rob them & turn them out on the street...
So as you can imagine, this is a very loaded term, particularly if you speak to anyone over the ages of ~35-40 about it.
Via social media & spread outside the Black community, the term's usage has shifted to mean just the people whose appearance would allow them to "pass for white" as a verb— people who are "lightskinned + ethnically ambiguous in a way approaching whiteness." It's also used to accuse "white passing" people of color of not actually being their race, or of racefaking & Blackfishing like those aforementioned 23andMe 1.5%ers, when that has never been how the term was used, nor how multiracial or lightskinned people of color have been legally or socially classified for centuries up until around the 2010s. There's always been intracommunity friction within multiple ethnic groups around the subject, like when someone "acts too white," "acts too Americanized," or is seen as barely x, y, or z, but within majority American culture— specifically in the US, specifically in the eyes of white America— "white passing" has never meant "accepted as white," and has always been a term ultimately centered on people of color's inherent exclusion from whiteness, even if you manage to "lie your way into the club," because all it takes is a hint of the truth of who you are to take it all away from you in a second.
And you lose all that understanding when you take Black terminology & Black scholarship & Black language for granted, because ALL THREE of these terms come from Black people— lightskinnededness & ethnic ambiguity are terms from us, too, that highlight specific hierarchies & social perceptions of Black people as compared to and amongst ourselves. Colorism is a Black term. White passing is a Black term. These are all rooted within & watered from experiences of Black community...
Some of these things can apply to other communities & situations, but saying shit like "xyz actual white person is lightskinmed" is a nonsense sentence. Saying Jurnee Smollett or Tessa Thompson are ethnically ambiguous just because they're light is an outright lie. Zendaya & Doja are not white passing in either sense of the word. Even saying Carol Channing or Wentworth Miller or Mariah Carey are white passing is a stretch imo because those are some VERY light-bright high yellow individuals, but none have ever deliberately feigned whiteness— though I'm coming from a "learned this term in the '90s" point of view. Don't catch yourself out here acting foolish over stuff you don't even realize you don't know enough to talk about just because you wanna run your mouth on TikTok & Twitter over complete strangers' skintones, hair textures, noses, or family histories like some wannabe phrenologist, eugenicist, anthropologist of old.