pero - used like "but" sino - used like "rather," "but rather" or "instead" sin embargo - used like "however," or "nevertheless." no obstante - often corresponds to "in spite of," or "nevertheless." a pesar de - is often used like "despite." de todos modos - is often equivalent to "anyway." aunque - can be used like "even if," or "even though" depending on the level of probability that the action will occur.
Examples:
Me gustaría salir, pero no puedo. I would like to leave, but I can't.
José es alto pero no es fuerte. José is tall, but he isn't strong.
María no es alta sino baja. Mary isn't tall, but rather she's short.
Manuel no es rico, sino pobre. Manuel isn't rich, but rather he's poor.
Normalmente me gusta la cerveza, sin embargo esta marca no me agrada. I normally like beer; however, I don't care for this brand.
No obstante el calor, pasamos mucho tiempo afuera. In spite of the heat, we spend a lot of time outside.
En fin ganamos a pesar de la buena competencia. In the end we won despite the good competition.
Estaba lloviendo pero anduvimos en bici de todos modos. It was raining but we went biking anyway.
Aunque está tu hermano no nos ayuda. Even though your brother is there he won't help us.
Aunque esté tu hermano no nos ayuda. Even if your brother is there he won't help us.
Aunque estuviera tu hermano no nos ayudaría. Even if your brother were there he wouldn't help us.
There is also a group of terms for ideas that do not contrast, but rather support one another. For example:
así que - commonly used like "so" or "thus" por lo tanto - commonly used like "therefore" (somewhat formal in tone) por eso - has many uses like, "due to that," "because of this," or "that's why"
La película empieza a las siete así que tenemos que llegar un poco antes. The movie starts at seven so we have to get there a little before.
Por lo tanto, el tiempo de reacción es influido por la temperatura ambiente. Therefore, the reaction time is influenced by the ambient temperature.
Juan es muy bajo y por eso nunca ha jugado bien el básquetbol. Juan is very short and that's why he has never played basketball well.
Trabajé todo el fin de semana a pesar que estaba cansado. - I worked all weekend despite of being tired. Caminé cinco kilómetros a pesar de la lluvia. - I walked 5 kilometers despite the rain. Comiste mucho a pesar de que ibas de viaje. - You ate a lot despite of going on a trip. De todos modos no trabajé ayer. - Anyway, I didn't work yesterday. María vino de todos modos. - María came anyway. María corrió sin embargo llegó tarde. - María ran nevertheless she arrived late. Como sin parar aunque engordo cada día. - I eat without stop even if I get fatter every day. Aunque el examen ya fue yo quiero seguir aprendiendo. - Even though the exam is already over, I want to keep learning. No obstante, las actuales turbulencias financieras exigen mejor control. - Nevertheless, the actual finance turmoil requires better control.