I'm not sure about what your question is, since the first example is "lo" + adjective and the other is "lo" + past participle. Both constructions are so different.
But here are some notes on the use of "lo". It's not an exhaustive review, but you may find it useful anyway:
"Lo" can be used to make a noun composed of many items to talk about a general idea of what an adjective expresses:
- Lo hermoso = las cosas hermosas
- Lo peligroso = las acciones/cosas peligrosas
- Lo que sé = (todas) las cosas que sé
- Lo malo que dice = las cosas malas que dice
- Lo que decimos = las cosas que decimos
"Lo" can be used to stress a quality:
- Lo ágil que es = ¡Qué ágil es!
How nimble she is!
- Lo bondadosa que era la abuela. = Qué bondadosa era la abuela.
How kind-hearted was grandmother.
"Lo" before singular adjectives and possessive pronouns, refers to a specific characteristic of an inanimate thing:
- Lo bueno de Tomísimo es que siempre hay alguien que me ayuda.
The good thing about Tomisimo is that there is always someone who helps me.
- Te deseo lo mejor del mundo.
I wish you all the best in the world.
- Lo más importante es que te recuperes pronto.
What is most important is that you get well soon.
- A Juan le encanta lo caro.
Juan loves expensive things.
- Lo mío.
My belongings/my business/my thing(s).
- Lo fácil es tener un hijo; lo difícil es educarlo.
The easy part is to have a child; what's hard is to raise it.
- No escuchaste lo más bonito del discurso.
You didn't hear the most beautiful part of the speech.
- Lo peor de mi trabajo es que tengo que trabajar los sábados.
The worst thing about my job is that I have to work on Saturdays.
- Lo extraño es que haya un político honesto.
The strange thing is that there may be an honest politician.
- Saqué todo lo inservible de mi casa.
I took out all useless stuff from my house.
- Todo el mundo puede disponer de lo suyo como quiera.
Everyone can decide on what to do with what is theirs the way they want.
"Lo" + "adjective"/"adverb" + "que" expresses some amount of something abstract. It emphasizes or intensifies the quality of the adjective or the adverb:
- Si supieras lo mucho que te quiero.
If you knew how much I love you.
- Se enojaron por lo tarde que salí.
They got angry because I left so late.
- Con lo cerca que vivo de mi trabajo, siempre puedo venir a comer a casa. I live so close to my job that I can always come home for lunch.
- Cada vez que trato de explicar esto, me doy cuenta de lo complicado que es.
Each time I try to explain this, I realize how hard it is.
- Me voy a enfermar si tomo el agua con lo fría que está.
I will fall sick if I drink this water as cold as it is.
- No saben lo triste que está Sebastián.
You don't know how sad Sebastian is.
- Había olvidado lo bonito que es este paisaje.
I had forgotten how beautiful this landscape is.
Direct object as reference to an idea that has already been expressed before:
- No creo que Pedro termine el trabajo. -> No lo creo.
I don't think that Pedro will finish the job. -> I don't think that.
- No entiendo por qué siempre haces las mismas preguntas. -> No lo entiendo.
I don't understand why you always ask me the same question(s). -> I don't understand it.
(Side note here: You could say "…por qué me preguntas lo mismo" -> "lo mismo" = "las mismas cosas")
- Está lloviendo; lo sé porque me duelen los huesos.
- It's raining, I know it because my bones are aching.
- No sé cuándo llegó el hombre a la Luna. -> No lo sé.
I don't know when the man reached the moon. -> I don't know it.
- Lo dije y lo repito: ¡eres un genio!
I've said it and I'll say it again: you're a genius!
—Me dijeron que te accidentaste. (I was told you had an accident.)
—¡No me lo recuerdes, fue espantoso! (Don't remind me about it, it was horrible!)
"Lo" + "de" is used to talk about a situation that we prefer not to mention with all its words, either because it would not be prudent or because it might be too long for a conversation:
- (You lost your job.) Entiendo que estés enojado por lo de tu despido.
-> I understand that you're angry about the whole situation that led to your being fired.
- (Someone's grandfather died.) Siento mucho lo de tu abuelo.
-> I'm sorry about what happened to your grandfather.
- ¿Cómo va lo de tu juicio?
-> How's your trial thing going?
One last note: "lo" always precedes its modifier, so the order of the words matters:
- Veo lo que es importante. /- Veo lo importante que es.
I see what is important. / I see how important it is.
- Preocúpate de todo lo que está mal. / - Preocúpate de lo mal que está todo.
Worry about all that is wrong. / - Worry about how wrong it all is.