They have completely different meanings. I recommend finding them in a monolingual dictionary like Oxford or Merriam Webster and then asking for any specific clarification.

Trend has an R in it and Tend doesn't.

Hi Dinghui, Tend is a verb with 4 different meanings; 1, To describe what often happens/ is likely to happen; 2, thoughts or views that generally have a particular quality; 3, to take care of/ look after someone or something (often used for sick people and gardens); 4. To serve customers in a bar or shop. Trend is a noun used to describe a general direction in which a situation is changing or developing. It has recently acquired a new adjectival form, specifically describing something or someone on social media that has a surge of popularity. Hope that’s useful. Helen

Hi Dinghui, the main diffrence is "trend" typically refers to a much more specific period of time or a more specific situation . "tend" has another meaning (care for or manage someone or something or to do something, or to have a certain characteristic. ) Examples: Trend : -Bieber is most beholden is the current trends in pop music. -What topics have been trending on social networks this week? Tend: -We need to tend to the garden, which has become a mess. -It tends to snow here in winter. -They tend to go out on Saturdays.