Jaký je rozdíl mezi touto powerbankou a touto: https://www.alza.cz/alzapower-onyx-20000mah-fast-charge-pd3-0-bila-d5683605.htm (ps: popřípadě jaká je lepší ?) Předem děkuji za odpověď.

A 36-month / 3-year or 48-month / 4-year warranty refers to the total duration of the warranty from the date of receiving the goods. Compared to standard statutory rights, this gives you an additional 12 months / 1 year or 24 months / 2 years, respectively, to file a claim.
Specifications can be changed without notice. Images are for illustrative purposes only.