如何(いかん)Depending on

次第だ・次第で indicates a cause-and-effect relationship where one outcome depends on another factor, as in 成功するかどうかは努力次第だ (Whether you succeed depends on your effort). 如何 means depending on more broadly, without implying a direct causal link, as in 天気如何で決まる (It will be decided depending on the weather).

Both expressions mean 'depending on' and can be used in similar contexts. For example, 実験の結果の如何で研究資金が決まる ('Depending on the results of the experiment, funding will be decided.') can be rephrased as 実験の結果次第で～ with no change in meaning. Note, however, that 次第 always attaches directly to nouns, while 如何 can connect either directly or with の. Also, 如何 is used in certain set expressions like ～の如何を問わず 'without considering' where 次第 is typically not used.

Both express that results depend on conditions, but the nuance and construction differ. ようによっては means ‘depending on how something is seen, used, or handled,’ and highlights that the same thing can lead to different outcomes based on circumstances or perspective, as in この映画は見ようによってはコメディーだと感じる人もいるだろう ('Some people may see this movie as a comedy, depending on how they watch it.'). 如何 is a formal, written expression meaning ‘depending on,’ used to state that an outcome is determined by a specific factor in an objective or structural way, as in 対応如何で結果が変わる ('The outcome will change depending on the response.').

Both can express that something is dependent on something, but their usage differs. にかかっている is used at the end of a phrase or sentence, e.g. 開催できるかどうかは天気にかかっている ('Whether or not we can hold the event depends on the weather.'). In contrast, 如何 can be used in mid-sentence in forms like ～の如何で or ～の如何によって, e.g. 君の努力の如何によって 'depending on your effort…'. Because of the overlap in meaning, they can even be used together for further emphasis, i.e. ～如何にかかっている 'depending on'.

如何 indicates that something depends on conditions, often formal, as in 成否は努力いかんだ (Success depends on effort). ふうに describes the manner or style of something, often casually, as in 彼は変わったふうに話す (He speaks in a strange way).

如何 (read as いかん) is a formal term meaning 'how' or 'in what way', used mainly in formal or academic writing. It appears after nouns, often in the pattern 如何によって ('depending on'). 状況の如何で決まる = 'It will be decided depending on the situation.' ように is a more common, casual form, e.g. 忘れないようにメモした ('I took a memo so I wouldn't forget.').