I am British, so you will see words like analyse, centre, colour, dived, licence and travelled (rather than analyze, center, color, dove, license and traveled). I use ‑ise endings rather than ‑ize endings (both are okay in British English but I prefer to apologise rather than to apologize).
Chemical names are spelt using IUPAC recommendations. This means you will see aluminium instead of aluminum (sorry USA), but sulfur instead of sulphur (sorry UK).
I use SI units for quantities, sometimes called metric units. For example, you will see metres, kilograms and cubic decimetres (but not feet, pounds and gallons).