whats the difference between bo-ru and tama

I just started learning japanese and couldn't find anything on the difference between these two. Don't they both mean ball? Are they the same thing and can be used interchangably?

I feel the distinction is similar to ball vs. sphere. Basically the same, but not quite.

ボール is ball (same sound and meaning), the word just coming from English,
https://en.wiktionary.org/wiki/%E3%83%9C%E3%83%BC%E3%83%AB
("bowl" is written in "ボウル" mainly but often using ボール ,too)
foreign lang that is no need to translate into Japanese is written in Katakana as same sound usual.

球(tama) is sphere also included "ball" case a lot, some items 玉(mentioned below) also instead.
https://en.wiktionary.org/wiki/%E7%90%83
https://dictionary.goo.ne.jp/jn/138632/meaning/m0u/%E3%81%9F%E3%81%BE/

Others :
玉(tama) is treasure, precious stones mainly, but.
https://en.wiktionary.org/wiki/%E7%8E%89
弾(tama) is bullet, but not only for weapons.
https://en.wiktionary.org/wiki/%E5%BC%BE
多摩(tama) is famous town area in west of Tokyo.
https://en.wikipedia.org/wiki/Tama_Hills
たま(tama) is one of very famous traditional male cat name :)
https://en.wikipedia.org/wiki/Tama_and_Friends
https://en.wikipedia.org/wiki/Tama_(cat)
(Already, Japanese name is a minority.)

And some other Kanjis and meanings.
https://dictionary.goo.ne.jp/srch/en/たま/m0u/

For Gundam fans, would like to touch this mobile suit named ボール,too :)
http://gundam.wikia.com/wiki/RB-79_Ball
https://youtu.be/U3Kk6ZElm4g (skip to 16:55)

They mean the same, but are not interchangeable (at least I cannot find a case they are interchangeable). There is a third word for the same thing "mari" that is less used, also. When to use which, I am not sure if there is a hard rule. Looking at the example list below, it might depend on the size, the origin (foreign or domestic), or the sound of the word. Some examples:

TAMA (including -dama): けん玉 kendama, ピンポン玉 ping pong ball, パチンコ玉 pachinko ball, 水玉 (みずたま) water droplet or polka dot, etc.

BO-RU (ball): テニスボール tennis ball, サッカーボール soccer ball, ビーチボール beach ball, etc.

MARI まり: 蹴鞠 (けまり) kemari, 手まり (てまり) temari, etc. (Both are ancient Japanese games that use spherical objects.)

You guys are forgetting about the most sensitive たま of them all: きんたま! ^_^ It's counter-intuitive because we say "balls" for the male body part and Japanese don't say ボール but say きんたま。Easy way to remember it is that the kanji 金玉（きんたま）literally means "golden ball/sphere". Males have golden balls. ^_-

"Tama" is anything sphere-shaped, although people do have the impression that "tama" is nothing bigger than a building. Also, as mentioned, bullets can be called "tama" too, and that probably comes from the fact that bullets were originally spheres.

The word "Boru" is used to mean western style balls for playing, especially those that are not so tiny and hard. Basketballs, baseballs, beach balls, small rubber balls for children are all "boru" among many others. These "boru" can also be called "tama". So as long as you're using the word in that context, the two words are interchangeable. Rugby balls can be called "tama" too, even though they're oblong.

Things like pinball balls, billiard balls and golf balls tend to be referred to as "tama" rather than "boru", but they're often called "boru" too.

Basically, traditional Japanese balls are called Tama and made of solid wooden core. Hanabi fireworks fire balls are also called Tama and people yell Tama-ya (Firework shop) when they explode in sky. Sparkler fire balls are also called tama when they form and drop.
All imported sport game balls are called balls and often air filled core. However, there are exceptions, i.e. billiard balls are tama, etc.