Shenzhen IO character differences
The first character looks a bit different. Is this just a different font, or is it a different character?

Unicode treats them with the same codepoint (U+6DF1), so it's the same character according to digital standards.

The difference in appearance is usually due to fonts, which adhere to different standards across the regions which use Chinese characters.



Mainland Chinese standards use a「八」shape, while other regions usually use a「儿」shape. If you're seeing「儿」then your fonts are not designed according to the Mainland Chinese standard.


  We now have super-families of fonts like Noto CJK which accommodate for both differences in orthography (character variations) and (minor) differences in regional shapes, so you can get (for example) a text which has Simplified Chinese but with the non-Simplified characters as Korean shapes.
  
  The exact font you're using to display those characters is Noto Sans CJK JP.
  
  
  
  Minor differences exist in all standards; your browser thinks the text language is Japanese, or defaults it to Japanese.


If you're learning Chinese characters not specifically from Mainland China, write it with「儿」.




  For reference, that component was originally「穴」, which depicts a cave dwelling (窯洞). The two strokes under「宀」was an abstract depiction of ventilation passages or air currents.
  
  楚簡新甲3.83　
  
  The structure of「深」has changed like the following over the years:
  
  西周金・隸定乖伯歸夆簋「罙」集成4331楚簡上(1)・孔・2　秦簡睡・雜15　現代楷　
  
  As can be seen,「八」or「儿」is just an approximation of a shape, and neither character actually features as a component in「深」. Shuowen's description
  
  
    「穴」，土室也。从「宀」，「八」聲。
    
    「穴」(Baxter-Sagart Old Chinese: /*[ɢ]ʷˤi[t]/), earthen dwelling; from semantic「宀」(building) and phonetic「八」(/*pˤret/).
  
  
  is very likely to be incorrect.
  
  
  
  References:
  
  
  季旭昇《說文新證》
  李學勤《字源》
  小學堂
  國學大師