Zakah purifies your wealth, is one of the five pillars of Islam, and is expected to be paid by all practicing Muslims who have the financial means (nisab). In addition to their zakah obligations, Muslims are encouraged to make voluntary contributions (sadaqat).
Between Zakah (Charity), Infaq (Donation), Sadaqah and Waqaf has its own meaning in the discussion of the books of fiqh. Zakat is liability for a specific property in a specific time and for a particular group.
Infaq (Donation) has a wider meaning of Zakat, which is issued or spend money. No donation is compulsory, sunnah and permissible. Infaq shall include zakat, expiation, donation to the family and so on. Infaq sunnah are strongly encouraged to do so, but not an obligation, as donation for the mission, the construction of mosques and so on. while Infaq Mubah which is not permissible in the category of obligatory and Sunnah, as well as there is no suggestion textual verses and the hadith, such as infak to take a bite to eat and so on.
Sadaqah broader than just charity or donation . Because Sadaqah is not just simply mean spending or donating property. However Sadaqah covers any charity or good deeds . Described in a hadith, ” Giving smile for your brother is charity. ”
Sadaqah meaning contained in the above hadith is referring to the meaning of Sadaqah above. Even implicitly intended Sadaqah in the Hadith are all forms of good that is done by every Muslim in order to seek the pleasure of Allah swt . Either in the form of worship or deeds
which is seen as a form lahiriyah taqarrub to Allah or in the form of activity which does not seem like lahiriyah bertaqarrub to God, such as the intimate relationship of husband and wife, work , etc.