Which is better for everyday office work?

Both handle documents, email and spreadsheets well at 1600x900. The E2026H is the smoother experience because of its 100 Hz refresh rate and HDMI input.

Is the 100 Hz refresh rate worth stepping up for?

Yes if you scroll long pages or drag windows all day; motion looks cleaner than at 60 Hz. If the screen mostly shows static text, the difference is small.

Which has better connectivity?

The E2026H. It has HDMI, DisplayPort and VGA, while the E2020H has only DisplayPort and VGA, so some laptops and mini PCs need an adapter.

Do either of these work with a monitor arm?

The E2026H is listed as VESA mount compatible. The E2020H specs do not list VESA support, so check the back of the unit before buying an arm.

Are the picture and viewing angles the same?

Largely yes. Both use TN panels at 1600x900, 250 cd/m² and 5 ms, with 170°/160° viewing angles, so colors shift when you view from below.

Both are built for office use and Dell backs its monitors with a multi-year warranty. There is no reliability data separating them; the E2026H is simply the newer design.

Dell E2020D 20-Inch Monitor vs Dell Pro 20 Monitor E2026H

Both are 20-inch 1600x900 TN office monitors from Dell, so the real split is ports and refresh rate. The E2026H adds HDMI and runs at 100 Hz, which makes scrolling and window dragging noticeably smoother and fits more devices without an adapter. The E2020H is the older, plainer unit: DisplayPort and VGA only, 60 Hz, tilt-only stand. For a basic desk display either works, but the E2026H is the better long-term pick for most people.

Choose the Dell E2020H if you only need a second screen for documents and email and your PC connects over DisplayPort or VGA.
Choose the Dell Pro 20 E2026H if you want HDMI, smoother 100 Hz motion and a newer model that is easier to connect to laptops and mini PCs.

Prices

Dell E2020D 20-Inch Monitor: $63.84 at dealtargets USA (last seen Nov 13)