They all have distinct meanings individually but it sounds like you're referring to their use as conjunctions or transition words. This is also probably why they sound like they have the same meaning. As transition words: - "However" and "yet" are used to introduce an idea that contrasts/contradicts what was already said; - "Anyway" and "anyhow" are considered informal and usually used to change a topic. Their definitions however: - "However" means "in whatever way/manner;" - "Yet" can either mean "up until now" or used to emphasise repetition/increase; - "Anyway" actually means "any manner/method" and can also be used to confirm or emphasise what was already said; - "Anyhow" means "in a careless/haphazard way."