Is SPI Flash memory faster than SD Card?

I need to log some data in my project based on ESP8266, most important for me is write/read speed. What is faster SPI Flash or SC Card?

Many (all?) SD cards internally use SPI flash memory, so the question seems pointless, especially since SD cards and SPI flash memory are available with various speeds.

I think that you will have to do your own testing, concentrating on what is important to you. For most applications, the interface is much slower than the actual memory device, but this may not always be true, for example if you plan to do a lot of erasing (which would be a bad thing).

Thanks, you help me a lot. I previously think that SD Card and SPI Flash are completly diffrent things. I try then SD Card and binary mode read/write

If you want a file-system like interface, use an SD card.

If you want byte-oriented access, use SPI flash (or EEPROM if you don't need the capacity).

Also, when people say that data access speed is critical to them, that's a red flag that they may be using the wrong tool for the job, as arduino isn't usually appropriate for that. It's hard to say without knowing more about what you're doing and your requirements.